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Age at puberty in bovine heifers is controlled largely by genetic and environmental factors, among which nutrition has a major influence. This study evaluated the utility of cool-season forages for heifer development in a limited-resource beef cow-calf system. Beef heifer development was evaluated at 4 time periods: Period 1 (Birth-Weaning) heifers sucked dams until weaning, Period 2 (Weaning-Puberty) heifers grazed natural pastures and supplements in Fall and Winter, Period 3 (Puberty-Breeding) heifers grazed cool-season forages, Period 4 (Breeding-Pregnancy) heifers were maintained on Spring and Summer forages. The supplements were fed at a rate of 0.45 kg/68.2 kg. calf BW and consisted of a 1:1 ratio of cracked corn and commercial grower pellets. Cool-season pasture consisted mainly of Rye grass and clovers. Hay, water, and minerals were provided free choice. Heifer body weights were obtained at quarterly intervals. They were synchronized with two doses of prostaglandin F (PGF) 2a, 14 days apart before bull introduction on June 1st. Pregnancy was confirmed by ultrasonography at the end of breeding in August. The growth trajectory was evaluated by mixed procedures of SAS. A stair-step pattern of body weight gain was observed from birth to pregnancy. There was rapid growth pre-weaning, average daily gain (ADG) = 0.95 ± 0.0.17kg ·heifer-1·day-1. Limited growth during the juvenile period (ADG = 0.24 ± 0.17kg·heifer-1·day-1) and compensatory growth during the pre-pubertal period (ADG = 1.32 ± 0.17kg·heifer-1·day-1). These preliminary results indicate that limited-resource beef cow-calf producers should utilize winter forages to leverage compensatory growth in their heifer development programs. Funded by FAMU World Class Scholars Program and NIFA CBG # 2021-38821-34599. [ABSTRACT FROM AUTHOR]

Tall fescue (Schedonorus arundinaceus) is the predominant cool-season perennial forage in the Eastern U.S. However, a symbiotic endophyte reduces performance of animals grazing tall fescue. This results in losses of around $2 billion annually. Due to the vasoconstriction caused by the endophyte, a decrease in conception rates among cows and heifers consuming tall fescue has been observed. With rising input costs, it is necessary to explore alternative mitigation strategies these production losses. The objective of this study was to mitigate the toxic effects of 'KY 31' tall fescue by limit-grazing cool-season annuals as an alternative to feed supplementation. In January 2022, 48 heifers [14 months of age; 365.9 ± 11.89 kg body weight (BW)] were randomly assigned to tall fescue only, tall fescue with supplemental feed at 1% of BW, tall fescue with limit grazing of cool-season annuals for 24 h per week, and cool-season annuals only. Four animals grazed in each of three replicated paddocks per treatment. Cool-season annual pasture was a mixture of crimson clover (Trifolium incarnatum), annual ryegrass (Lolium multiflorum), and oat (Avena sativa). Body condition scores (BCS), hair coat scores (HCS), and BW were recorded every 30 d. Forage samples were taken for biomass, nutritive value, and ergovaline concentration every 30 d. On April 1, 2022, heifers were artificially inseminated (AI), and conception rates were determined 45 d after AI. Data were analyzed using the Glimmix procedure of SAS 9.4 (SAS Inst, Cary, NC) with a = 0.05. There were no differences among treatments in HCS at any weigh date (P > 0.05). The BCS for all treatments was less in February than January or March (5.6, 6.1, 6.1, respectively; P < 0.0001), but there were no differences among treatments at any sampling date (P > 0.05). Conception rates were not different among treatments (P > 0.10) but averaged 75, 67, 42, and 50% for the continuous-cool season, limit graze, supplemental feed, and tall fescue treatments, respectively. Crude protein (CP) concentrations for the control and limit grazing fescue treatments were greater than the limit grazing cool-season annual treatment, continuous grazing cool-season annual treatment, and the supplemental feed treatment (13.5, 10.7, 10.4, and 8.9%, respectively, (P < 0.012). Neutral detergent fiber (NDF) and acid detergent fiber (ADF) were different among the supplemental treatment when compared with the limit grazing fescue, limit grazing cool-season annual, control, and continuous cool-season annual (48.2 vs 64.7% NDF and 25.8 vs. 37.0% ADF; P < 0.0361). At this time, the results indicate that limit grazing coolseason annual forages may be an advantageous option to mitigate fescue toxicosis in replacement heifers grazing tall fescue pastures in the spring. [ABSTRACT FROM AUTHOR]

The objective of this study was to evaluate the effects of concentrate supplementation levels on performance and DM intake of early-weaned beef calves consuming annual ryegrass (Lolium multiflorium). The experiments were conducted at the UF/IFAS Range Cattle Research and Education Center, Ona, FL from January to May 2022. In experiment 1, treatments were two levels of concentrate supplementation (0.75% or 1.0% of BW) distributed in a randomized complete block design with four replicates. Concentrate was fed daily and had 18% CP and 78% TDN. Thirty-two Angus crossbred calves were weaned with 90 ± 14 kg BW at 76 ± 10 d of age and allocated to 1 of 8 annual ryegrass pastures (experimental units; 0.3 ha/pasture; 4 calves/pasture) with a continuous and fixed stocking rate. Herbage mass and nutritive value were estimated every 14 d and calves were weighed every 28 d. There was no difference in herbage mass (mean = 1.300 kg DM/ha; P = 0.44; SE = 0.46), herbage allowance (mean = 0.86 kg DM/kg LW; P = 0.66; SE = 0.03), CP (mean = 24.4%; P = 0.46; SE = 0.78), and in vitro digestible organic matter (mean = 77%; P = 0.49; SE = 1) concentration between treatments. There was a treatment × month interaction on ADG and the interaction occurred because calves receiving 1% BW had greater ADG than 0.75% BW in April (1.0 vs. 0.8 kg/d; P = 0.04; 0.03) but there were no differences between treatments in February, March, and May. In experiment 2, treatments were supplementation with 0.75% or 1.0% BW concentrate distributed in a complete randomized design with seven replicates. Fourteen steers calves (166 ± 17 kg BW) from experiment 1 were maintained in the same treatment, transferred to a drylot (1 steer/pen), and evaluated for forage and total DM intake, and in vivo DM digestibility. Ground annual ryegrass hay (11% CP, 58% IVDOM) was offered and adjusted to allow 10% refusals. There was no difference in forage DM intake (mean = 1.8 kg DM/d; P = 0.3; SE = 0.06) between treatments but calves receiving 1.0% BW had greater total DM intake (2.7 vs. 2.5 kg DM/d; P = 0.05; SE = 0.06) and in vivo DM digestibility (77 vs. 75%; P < 0.01; SE = 0.53) than 0.75% BW. Decreasing concentrate supplementation level from 1.0 to 0.75% BW may be a viable management practice to reduce cost of developing early weaned beef calves grazing annual ryegrass. [ABSTRACT FROM AUTHOR]

Bovine respiratory disease (BRD) is the leading cause of morbidity and mortality in beef cattle. Common management practices in addition to BRD have been shown previously to cause inflammation. The objectives of this study were: (1) characterize the inflammatory profiles as indicated by haptoglobin concentrations, over a receiving period in high-risk cattle; (2) evaluate the impact of on-arrival metaphylactic antimicrobial therapy on inflammatory profiles in high risk cattle; and (3) examine the relationship between inflammatory profile and BRD morbidity and mortality in high risk cattle. This 70 d trial was repeated over two years. A total of 160 black/black white face crossbred heifers were acquired from local auction markets and randomly assigned at arrival to treatment groups. Heifers were purchased by an order buyer from auction barns. At arrival, heifers were randomly assigned to either receive tulathromycin (Draxxin, META, n = 40) or not (NO META, n = 40) upon arrival. Each group was housed on a 10-acre pasture planted in annual ryegrass where they were offered complete commercial supplemental feed (14% CP) and free choice (both Purina Animal Nutrition, Nashville, TN) mineral and were observed daily for clinical signs of BRD. Cattle were weighed and blood was collected every seven days from d0 to d20, and again on d70. Haptoglobin concentrations were determined using ELISA. Effects of treatment and morbidity on haptoglobin concentration were tested using the MIXED procedure of SAS. Overall morbidity was 28.5%. Initial body weight (227 kg META, 229 kg NO META, P > 0.10) did not differ between the two treatment groups. However, final body weight differed between treatment groups (294 kg META, 289kg NO META). Haptoglobin concentrations remained elevated over time for all groups (P = 0.03). Metaphylaxis did not affect haptoglobin concentration (P > 0.10). There was a significant increase in BRD cases from day 0 to 20 (P = 0.00). Morbidity (BRD vs no BRD) did not impact haptoglobin concentrations. Overall, metaphylaxis did not affect haptoglobin levels or BRD incidence. [ABSTRACT FROM AUTHOR]

Nitrogen excretion from sheep production systems is an important source of nitrate, ammonia, and nitrous oxide responsible for groundwater pollution and global warming. The present study aimed to identify key parameters influencing N utilization efficiency and develop prediction equations for manure N, feces N, and urine N outputs in sheep. Data used were collected from 82 sheep offered fresh perennial ryegrass (Lolium perenne) as the sole diet in 6 metabolism experiments (data from non-grassonly diets were not used). Sheep were from breeds of Highlander, Texel, Scottish Blackface, and Swaledale at the age of 5 to 18 mo and weighing from 24.5 to 62.7 kg. Herbage was harvested daily from 6 swards of contrasting harvest dates (May to December), offering wide variation in feed value to cover the range that would be offered in most practical farm situations. Before the commencement of each study, the experimental sward was harvested at a residual height of 4 cm and allowed to grow for 2 to 4 wk to target an average pregrazing sward height in a range of 8 to 15 cm depending on the time of year. Sheep were housed in individual pens for 14 d and then transferred to individual metabolism crates for 4 d with feed intake and feces and urine outputs measured. Data were analyzed using the linear mixed model procedure to develop prediction equations for feces N, urine N, and manure N outputs using N intake, herbage chemical composition, and digestibility with effects of sex, breed, and experimental periods removed. Nitrogen intake was the best single predictor for N output in feces, urine, and manure, and the r² value for prediction of manure N output was greater than those for feces N and urine N (0.86 vs. 0.70 and 0.77, respectively; P < 0.001). Animal BW and herbage DM, ether extract, NDF, ADF, water soluble carbohydrate, and DE concentrations and N digestibility were also used to predict N outputs because N intake may not be available in commercial practice. The prediction equations for N utilization efficiency indicated that increasing feeding level and ME concentration and reducing N concentration could improve N utilization efficiency and shift N excretion into feces rather than urine (P < 0.001). The equations developed in the current study provide an approach for sheep producers to quantify N excretion against production and, consequently, to develop their own mitigation strategies to reduce the environmental impact of sheep production systems. [ABSTRACT FROM AUTHOR]

Remote sensing has opened doors for grazing management by allowing producers to monitor forage in a more efficient way. The objective of this study was to observe the relationship between the normalized vegetation index (NDVI) from images taken by an unmanned aerial vehicle (UAV) to nutritive value parameters. This project took place at the H. H. Leveck Animal Research Center located in Starkville, MS where 9, 2-hectare pastures planted in Marshall annual ryegrass (Lolium multiflorum) were utilized. Each 2-hectare pasture was subdivided into 0.20-hectare sections where forage samples were collected from 3, 1/4 of a meter quadrat every 14-days. Images were taken with UAV over a 76-day grazing period every 14-days. Images from the UAV were captured at 121.9 m above ground level using a DJI inspire 2 rotor wing fitted with a MicaSense RedEdge camera (MicaSense; Seattle, WA). Images were processed using Pix4D (Pix4D SA; Prilly, Switzerland) and analyzed in QGIS (QGIS; OSGeo; Finland). Raster calculator in QGIS was utilized to calculate NDVI values. Forage samples were analyzed using NIR for crude protein (CP), acid detergent fiber (ADF), neutral detergent fiber (NDF), relative forage quality (RFQ), and invitro dry matter digestibility (IVDMD) and correlated to NDVI values. Regression analysis was conducted in R (RStudio, PBC) using the package easynls (easynls-package) procedure within package ggplot2 (ggplot2-package). Regression models were obtained through a backward-elimination technique. Neutral detergent fiber (r² = 0.27) had the best correlated relationship to NDVI compared with CP (r² = 0.21), ADF (r² = 0.25), RFQ (r² = 0.18), and IVDMD (r² = 0.22). As NDVI values increased, CP, RFQ, and IVDMD increased while ADF and NDF decreased. There was a weak correlation between all nutritive value parameters and NDVI values. In conclusion, weak relationships indicate that NDVI values may not be the best predictor of nutritive value. [ABSTRACT FROM AUTHOR]

Development of effective methane (CH4) mitigation strategies for grazing sheep requires accurate prediction tools. The present study aimed to identify key parameters influencing enteric CH4 emissions and develop prediction equations for enteric CH4 emissions from sheep offered fresh grass. The data used were collected from 82 sheep offered fresh perennial ryegrass (Lolium perenne) as sole diets in 6 metabolism experiments (data from non-grass-only diets were not used). Sheep were from breeds of Highlander, Texel, Scottish Blackface, and Swaledale at the age of 5 to 18 mo and weighing from 24.5 to 62.7 kg. Grass was harvested daily from 6 swards on contrasting harvest dates (May to December). Before the commencement of each study, the experimental sward was harvested at a residual height of 4 cm and allowed to grow for 2 to 4 wk. The feeding trials commenced when the grass sward was suitable to zero grazing (average grass height = 15 cm), thus offering grass of a quality similar to what grazing animals would receive under routine grazing management. Sheep were housed in individual pens for 14 d and then moved to individual calorimeter chambers for 4 d. Feed intake, fecal and urine outputs, and CH4 emissions were measured during the final 4 d. Data were analyzed using the REML procedure to develop prediction equations for CH4 emissions. Linear and multiple prediction equations were developed using BW, DMI, GE intake (GEI), and grass chemical concentrations (DM, OM, water-soluble carbohydrates [WSC], NDF, ADF, nitrogen [N], GE, DE, and ME) as explanatory variables. The mean CH4 production was 21.1 g/kg DMI or 0.062 MJ/MJ GEI. Dry matter intake and GEI were much more accurate predictors for CH4 emissions than BW (P < 0.001, r2 = 0.86 and r2 = 0.87 vs. r2 = 0.09, respectively). Adding grass DE and ME concentrations and grass nutrient concentrations (e.g., OM, N, GE, NDF, and WSC) to the relationships between DMI or GEI and CH4 emissions improved prediction accuracy with R2 values increased to 0.93. Models based on farm-level data, for example, BW and grass nutrient (i.e., DM, GE, OM, and N) concentrations, were also developed and performed satisfactorily (P < 0.001, R2 = 0.63). These models can contribute to improve prediction accuracy for enteric CH4 emissions from sheep grazing on ryegrass pasture. [ABSTRACT FROM AUTHOR]

Grazing management is heading towards a more digitized world where producers can use technology such as satellite imagery, drone imagery and global positioning system (GPS) data sets for matching real-time forage availability to livestock nutritional needs. The objective of this study was to compare vegetative indices between unmanned aerial vehicles (UAV) and satellite imagery to observe changes in forage mass in relation to environment and grazing pressure. This project took place at the H. H. Leveck Animal Research Center located in Starkville, MS where nine, two-hectare pastures planted in Marshall annual ryegrass (Lolium multiflorum) were utilized. Each pasture was monitored with a satellite and UAV over a 76-day grazing period with images taken every 14-days. Images from the UAV were captured at 121.9 m above ground level using a DJI inspire 2 rotor wing fitted with a MicaSense RedEdge camera (MicaSense®; Seattle,WA). Satellite images were captured using a constellation of satellites from Planet (Plant Labs Inc.; San Francisco, CA). Images were processed using Pix4D (Pix4D SA; Prilly, Switzerland) and analyzed in ArcGIS (ArcGIS; Esri; Redlands, CA). Normalized vegetation index (NDVI) was calculated for both imagery platforms. In addition, forage samples were collected for future analysis every 14-days to calculate biomass and observe forage nutritive value. Each UAV image was resampled using cubic convolution to match spatial resolution of the satellite image. Raster calculator in ArcGIS was utilized to calculate NDVI values between images. Reported NDVI value data were analyzed in the NPAR1WAY procedure of SAS® software, Version 9.4 (SAS Institute, Cary, NC, 2013). using a significance level of α = 0.05. Greenness of vegetation was significantly greater (P< 0.0001) for the UAV compared to the satellite imagery with NDVI being 0.80 compared to 0.78 respectively. In conclusion, vegetation observed by UAV imagery reports greater density of green vegetation. [ABSTRACT FROM AUTHOR]

Bermudagrass is often over-seeded with a cool-season annual grass for grazing purposes. In the Gulf Coast region, summer perennials will not become dormant until there are low soil and ambient temperatures. Nitrogen fertilizer is an expensive input and its split application for winter pastures is recommended. The objective of this experiment was to evaluate the time of application of N fertilizer or its substitution with red clover as a source of N. Three treatments were evaluated in 3 consecutive years (2 replicates per year) on annual ryegrass (cv. Marshall) no-tilled planted (45 kg/ha) on Tifton-85 bermudagrass: 1) Urea in late November and mid-late January; 2) Red clover planted with annual ryegrass; 3) Urea in January only. Thirty crossbred steers (203±24 kg) were blocked by BW and randomly assigned to 1 of 6 groups. Each group were continuously stocked on 1.34 ha pastures for 90 d. Forage mass, botanical composition, and nutritive value of the pastures were determined from the time of the first N application and every 15 d thereafter. There was treatment x year interaction (P = 0.03) in botanical composition. Greater proportions (P = 0.03) of bermudagrass were present on the 2-application treatment on every sampling date until d 15 of the grazing period in Year 1 and 3. This was a result of N absorbed by bermudagrass which impacted its nutritive value (P = 0.01) although not forage production (P = 0.07). In Year 2, annual ryegrass dominated the swards due to a cold artic front in early November. Steers grazing fertilized treatments had greater gains (P = 0.04), while production per ha was greater (P = 0.03) when N was applied in January than when no N was applied. Hay production (kg DM/ha) was similar (P = 0.06) among treatments. Opportunities for improved economics of production and enhanced sustainability appear to be realistic objectives with changes in fertilization strategy. [ABSTRACT FROM AUTHOR]

Grazing sward structure can influence animal performance in forage-only and forage plus concentrate-based production systems. The objective was to determine the effects of pre-grazing herbage mass (PGHM), postgrazing sward height (PGSH) and indoor finishing diet on performance of weaned, spring-born beef steers. Steers (n = 96, ca. 12 months of age, 396 ± 20.1 kg) previously fed grass silage only over the first winter, were assigned to one of twelve grazing groups, balanced for live weight. Grazing groups were randomly assigned to a two PGHM (1500 or 2500 kg DM/ha) × two PGSH (4 or 6 cm) factorial arrangement of treatments (n = 3 groups/treatment). Steers rotationally grazed Lolium perenne-dominant swards (not mechanically topped) for 222 days. Steers were then accommodated indoors and offered grass silage only (SO) or grass silage + 3.8 kg concentrate DM/head daily (SC) for a 146 day finishing period. Data were analysed using the mixed procedure of SAS with terms for PGHM, PGSH, finishing diet and their interactions in the model. Grazed herbage intake was unaffected by PGHM but was greater for PGSH-6 than PGSH-4 (6.94 vs. 6.18 kg DM/day; P < 0.001). Steer average daily gain at pasture was greater for PGHM-1500 than PGHM-2500 (0.65 vs. 0.60 kg; P < 0.05) and for PGSH-6 than PGSH-4 (0.70 vs. 0.55 kg; P < 0.001). After indoor finishing, carcass weight was unaffected by PGHM, but was heavier for PGSH-6 than PGSH-4 (386 vs. 367 kg; P < 0.01); carcass traits were unaffected by PGHM or PGSH. Carcasses were heavier (+43 kg), fatter (P < 0.001) and more conformed (P < 0.01) for SC than SO. In conclusion, both PGHM-2500 and PGSH-4 restricted animal growth at pasture; however, following an indoor finishing period, carcass weight did not differ between PGHM, but was heavier for PGSH-6 than PGSH-4. [ABSTRACT FROM AUTHOR]

A farmlet study was established to evaluate the effect of four sward types on the performance of heifers and lambs co-grazing: a perennial ryegrass only sward (PRG) receiving 170 kg N/ha each year; a permanent pasture (PP) receiving 135 kg N/ha each year; a six species mix (2 grasses, 2 legumes, 2 herbs) at 70 kg N/ha each year (6SP); and a 12 species mix (3 grasses, 4 legumes and 5 herbs) at 70 kg N/ha each year (12SP). Each farmlet (9 ha) was rotationally grazed with 20 dairy cross heifers (13 months old) and 22 ewes plus lambs from April to November 2020. Heifers and lambs were finished for slaughter from herbage only diets. Heifers were weighed monthly and drafted for slaughter on three occasions when their estimated fat class on the EUROP grid scale reached 3-. Lambs were weighed fortnightly and drafted for slaughter at 42 kg [lambing to weaning (July 7th)], 44 kg (weaning to September) and 46 kg (after September 1st) to obtain a target carcass weight of 21 kg. Average daily gain (ADG) was higher for heifers grazing the 6SP sward (1.13 kg/day) than the PRG (0.99 kg/day) or PP swards (1.03 kg/day; P < 0.05). Kill out percentage (KO%) was higher for heifers grazing the 12SP sward (48.9%) compared to the PP sward (47.2%; P < 0.01). Lamb ADG was higher for lambs grazing the 6SP sward (0.38kg/day) compared to lambs grazing either the PP (0.32kg/day) or the PRG sward (0.29kg/day) (P < 0.01). Lamb KO% was higher for lambs grazing the 12SP sward (49.4%) compared to those grazing the PRG (45.7%) and the PP swards (44.5%; P < 0.01). Lambs grazing the 6SP sward had reduced days to slaughter (109) compared to lambs grazing the PP (137) and PRG (149) swards (P < 0.01). In conclusion, co-grazing multispecies swards improved overall heifer and lamb performance. [ABSTRACT FROM AUTHOR]

Tall fescue [Lolium arundinaceum (Schreb.) Darbysh. syn. Festuca arundinacea Schreb.] and perennial ryegrass (Lolium perenne L.) are impor-tant perennial forage grasses utilized throughout the moderate- to high-rainfall temperate zones of the world. These grasses have coevolved with symbiotic fungal endophytes (Epichloe/Neotyphodium spp.) that can impart bioactive properties and environmental stress tolerance to the grass compared with endophyte-free individuals. These endophytes have proven to be very important in pastoral agriculture in the United States, New Zealand, and Australia, where forage grasses are the principal feed for grazing ruminants. In this review, we describe the biology of these grass-endophyte associations and implications for the livestock indus-tries that are dependent on these forages. Endophyte alkaloid production is put in context with endophyte diversity, and we illustrate how this has facilitated uti-lization of grasses infected with different endophyte strains that reduce livestock toxicity issues. Utilization of tall fescue and use of perennial ryegrass in the United States, New Zealand, and Australia are compared, and management strategies focused predominantly on the success of endophyte-infected perennial ryegrass in New Zealand and Australia are discussed. In addition, we consider the impact of grass-endophyte associations on the sustainability of pasture ecosystems and their likely response to future changes in climate. [ABSTRACT FROM AUTHOR]

The daily BW gain of stocker steers grazing tall fescue [Lolium arundiriaceum (Schreb.) S.J. Darbysh. = Schedonorus arundinaceus (Schreb.) Dumort.]-based pastures typically declines during summer. To avoid these declines, in part to mitigate the effects of tall fescue toxicosis, it is commonly advised to move cattle to warm-season forage during this period. A 3-yr (2006, 2007, and 2008) grazing study was conducted to evaluate the effect of replacing 25% of the area of a tall fescue/clover (81% endophyte-infected) pasture system with "Ozark" bermudagrass [Cynodon dactylon (L.) Pers.] overseeded with clover (Trifolium spp.) to provide summer grazing for stocker steers (TF+BERM). The TF+BERM treatment was compared with a grazing system in which tall fescue/clover (TF) pastures were the only type of forage available for grazing. Our objective was to determine if replacement of 25% of the land area in a fescue system with bermudagrass would increase annual beef production compared with a system based solely on tall fescue. The study was conducted at the Southwest Research and Education Center of the University of Missouri near Mt. Vernon. Each treatment was rotationally stocked with 5 steers (248 ± 19.3 kg) on 1.7 ha. Fertilizer applications were applied at rates recommended for each respective forage species. Total forage production, BW gain per hectare, and season-long ADG of steers was greater (P < 0.06) for TF+BERM than for TF in 2006, but none of these measures differed (P > 0.19) in 2007 or 2008. In vitro true digestibility of pastures was greater (P = 0.01) for TF (84.4%, SEM = 0.64%) compared with TF+BERM (80.6%, SEM = 0.79%), even in summer. The decreased in vitro true digestibility of the bermudagrass pastures likely negated any benefit that animals in TF+BERM had in avoiding the ergot-like alkaloids associated with endophyte-infected tall fescue. Renovating 25% of the pasture system to bermudagrass provided some benefit to the system in years when summertime precipitation was limited (2006) but provided no value in wetter years (2007 and 2008). Although renovating endophyte-infected tall fescue pastures to a warm-season forage is a widely used practice to mitigate tall fescue toxicosis, the benefits of this practice are limited if forage quality of the warm season component is poor. [ABSTRACT FROM AUTHOR]

Two experiments were conducted using laboratory mini-silos to study the effect of ensiling and silage additives on fatty acid (FA) composition, including minor or unusual FA, of ryegrass and corn silages. Ryegrass was ensiled for 12 wk with no additives, with the addition of a bacterial inoculant or formic acid. Corn was ensiled for 9 wk without additives, with the addition of a bacterial inoculant or calcium formate. Ensiling affected both total FA content and FA composition of ryegrass silages. Total FA concentration increased (P < 0.001) during ryegrass ensiling. The proportions (g/100 g of total FA) of the major unsaturated FA, 18:3n-3 and 18:2n-6, were not affected (P > 0.05) by ensiling. However, their concentration (mg/g of DM) in silages was greater (P = 0.017 and P = 0.001, respectively) than in fresh ryegrass. Two 18:2 FA (trans-11,cis-15 and cis-9,cis-15) that were not originally present in the fresh ryegrass were detected in silages. Silage additives affected the FA composition of ryegrass silages, mostly by increasing the proportions of SFA, but not on total FA concentration. Ensiling did not affect (P = 0.83) total FA content of corn silages; however, FA composition was affected, mostly by decreasing the proportions of 18:2n-6 and 18:3n-3. Silage additives had no effect on corn silage FA composition. Exposing corn silages to air resulted in no oxidation of FA or reduction in total FA content or composition. [ABSTRACT FROM AUTHOR]

An experiment was conducted to evaluate the effects of pasture finishing versus feedlot finishing, over time, on fatty acid metabolism in Angus crossbred steers (n = 24). Ruminal fluid, serum, and adipose tissue biopsies were obtained on d 0, 28, 84, and 140. Pasture forages and diet ingredient samples were obtained at 14-d intervals to determine nutritive value and fatty acid composition. The feedlot diet consisted of corn silage, cracked corn grain, soybean meal, and a vitamin and mineral supplement. The pasture-finished steers grazed sequentially on triticale (x Triticosecale rimpani) /annual ryegrass (Lolium multiflorum), alfalfa (Medicago sativa)/orchardgrass (Dactylis glomerata), and a cool-season grass/legume mixture. The feedlot diet contained an average of 57% of total fatty acids as linoleic acid and 2% as linolenic acid. The pasture forages contained 9% of total fatty acids as linoleic acid and 66% as linolenic acid. Concentrations (% of total fatty acids) of linolenic acid were greater (P < 0.05) in ruminal fluid, serum, and adipose tissue of the pasture-finished steers, compared with the feedlot-finished steers. Concentrations (% of total fatty acids) of cis-9, trans-11 CLA were greater (P < 0.05) in adipose tissue of the pasture-finished steers than feedlot-finished steers. Concentrations of cis-9, trans-11 CLA in adipose tissue declined (P < 0.05) in the feedlot-finished steers from d 0 to 28 to 84. In the pasture-finished steers, concentrations of cis-9, trans-11 CLA in adipose tis- sue (mg/g of tissue) peaked (P < 0.05) on d 28 and remained elevated (ranged from 9.91 to 12.80 mg/g of tissue) throughout the duration of the study. In the pasture-finished steers, linolenic acid concentrations tended to peak (P = 0.07) on d 28 and remained elevated (ranged from 0.64 to 0.80% of total fatty acids) throughout the study. It appears that only a short time is needed to alter the n-3 and CLA composition of adipose tissue in cattle finished on pasture. [ABSTRACT FROM AUTHOR]

ABSTRACT: Crossbred steers (n = 72) were selected to study forage-based finishing systems using winter annual ryegrass (Lolium m'altiflorum Lam.) with varying levels of grain supplementation. In December, cattle were allotted to 1 of 6 treatments consisting of ryegrass pasture (1 ha) with whole shell corn supplemented at 0.0% (0.0), 0.5% (0.5), 1.0% (1.0), 1.5% (1.5), and 2.0% (2.0) of BW, or an ad libitum mixed-ration grain diet in a drylot. Steers were randomly assigned to pens of 4 with pen serving as the experimental unit. Cattle were slaughtered by pen when average pen backfat thickness (as measured by real-time ultrasound) reached approximately 0.64 cm. Forage samples and disk meter height were taken from ryegrass paddocks on a monthly basis to determine forage quality and mass. Live animal performance, carcass traits, proximate analysis, WarnerBratzler shear force, and sensory characteristics from the LM of the rib section were analyzed. Increasing the amount of grain in the diet of finishing cattle resulted in a linear decrease (P < 0.05) in days on feed and a linear increase (P < 0.05) in ADG, preliminary yield grade, final yield grade, flavor intensity, and beef flavor. Forage DM mass increased with each incremental increase in grain added to the grazing diets. Quality of forage was not (P > 0.05) affected by adding grain to the diet. Adding corn to the diet of cattle being finished on forage improved animal performance and decreased forage utilization characteristics in addition to improving the flavor characteristics of beef. [ABSTRACT FROM AUTHOR]

ABSTRACT: The objective of this study was to investigate the differences in the muscle proteome of grassfed and grain-fed cattle. Eight Japanese Black Cattle 10 mo of age were separated randomly into 2 groups: 1) grazing (grass-fed) and 2) concentrate (grain-fed) groups. All cattle were first housed individually in a stall barn and fed a combination of concentrate ad libitum and Italian ryegrass hay until 21 mo of age. After this control period, the 4 grass-fed cattle were placed on outdoor pasture, whereas the other 4 grain-fed cattle continued on the concentrate diet. The cattle were slaughtered at 27 mo of age, and tissues from the semitendinosus muscle were obtained for use in proteome analysis. Differential expression of muscle proteins in the 2 groups was carried out using 2-dimensional gel electrophoresis (2DE) and Western blot analyses, with subsequent mass spectrometry. Approximately 200 individual protein spots were detected and compared in each group using 2DE, of which 20 and 9 spots, respectively, showed differences in the spot intensity for the sarcoplasmic fraction and myofibrillar fraction. In the grazing group, the relative intensity of spots was significantly greater for adenylate kinase 1 and myoglobin in the sarcoplasmic fraction, and for slow-twitch myosin light chain 2 in the myofibrillar fraction (P < 0.05), than the concentrate group. The relative spot intensity of several glycolytic enzymes was significantly greater in the grazing group, such as β-enolase 3, fructose-1,6-bisphosphate aldolase A, triosephosphate isomerase, and heat shock 27 kDa protein (P < 0.05). Moreover, significantly greater slow twitch of troponin T, troponin I, and myosin heavy chain of semitendinosus muscle was detected in the grazing group than in the concentrate group using Western blot analysis (P < 0.05). Several previous reports have described that the slow-twitch muscle contents affect elements of nutrition, flavor, and food texture of meat. This study revealed muscle fiber type conversion to slow-twitch tissues from fast-twitch tissues occurring with change in the energy metabolic enzyme when cattle were grazed in the latter fattening period. Although analyses of the influence on elements of nutrition, flavor, and food texture were not done for this study, these results show that slow-twitch converted muscle resulting from the grazing of cattle might modify several meat characteristics. [ABSTRACT FROM AUTHOR]

To investigate anthelmintic and nutritional effects of heather supplementation in goats grazing perennial ryegrass-white clover pastures, 40 dry Cashmere goats were randomly assigned to 4 treatments in a 2 × 2 factorial arrangement: 2 grazing management treatments (supplementation with heather vs. nonsupplementation) and 2 anthelmintic treatments (treatment vs. nontreatment). Goats grazed continuously from May to September 2004. At the end of the grazing period, the number of dead goats due to gastrointestinal parasitism was 1 in the group supplemented with heather and dosed with anthelmintic, 4 in the group that received neither supplementation nor anthelmintic, and 0 in the other 2 groups. For goats that did not receive anthelmintic treatment, the percentage of heather in the diet was negatively correlated with fecal egg count in August (r = -0.59, P < 0.05) and September (r = -0.49, P < 0.1) and positively correlated (r = 0.54, P < 0.05) with BW changes during the grazing season. Therefore, the correlation coefficient between BW change and fecal egg count was negative (r = -0.62, P < 0.05). Rumen ammonia concentrations were always lower in supplemented goats (P < 0.05). However, VFA concentrations were greater in goats consuming heather (58.9 vs. 50.9 mmol/L), which suggests that ruminal fermentation was not adversely affected by consumption of tannins. Heather availability in the vegetation might represent a valuable opportunity and sustainable method to control gastrointestinal nematode infections in a goat production system based on grazing perennial ryegrass-white clover pastures. [ABSTRACT FROM AUTHOR]

Two experiments were conducted to evaluate the effect of species of cool-season annual grass on the growth of stocker cattle over 3 yr. In Exp. 1, the small grains (SG) oat (0), rye (R), and wheat (W), or combinations of SG and annual ryegrass (RG), were interseeded into Bermudagrass sod in a completely randomized design with a 3 × 2 factorial arrangement of treatments. In Exp. 2, RG was planted alone or with 0, R, triticale (T), or W in a completely randomized design. Pastures were planted in late October of each year, and seeding rates were 134.4 and 22.4 kg/ha for SG and RG, respectively. In Exp. 1, grazing was initiated on December 18. In Exp. 2, grazing was initiated on December 23 for SG pastures and January 21 or February 16 for RG pastures in yr 1 and on December 8 for all pastures in yr 2. Grazing was managed using the put-and-take method, in which additional calves were added as needed to maintain equal grazing pressure among pastures. In Exp. 1, no interactions (P ≥ 0.28) were detected, so the main effects of SG species and RG addition are discussed. From December 18 to March 12, there were no differences in ADG (P ≥ 0.17), whereas during the spring (from March 12 to May 7), addition of RG increased (P = 0.05) ADG. Using RG increased (P ≦ 0.01) animal grazing-days/hectare and BW gain/hectare. Wheat tended (P = 0.08) to increase BW gain/hectare compared with the other SG, and 0 tended (P = 0.09) to produce less BW gaimfhectare than the other SG. The treatment × year interaction was significant (P ≦ 0.05) in Exp. 2. In yr 1, no differences (P = 0.25) were observed for AUG from December 23 to March 8, but during the spring grazing period (from March 8 to May 5), ADG of calves grazing TRG was less (P ≦ 0.04) than that of those grazing RG, RRG, or WRG. The RRG combination produced more (P ≦ 0.03) BW gain/hectare than ORG, RG, or TRG and tended (P = 0.06) to produce more BW gain/hectare than WRG. The WRG combination produced more (P ≦ 0.05) BW gain/hectare than TRG and RG, and ORG tended (P = 0.09) to produce more BW gain/hectare than RG alone. Pastures planted to R or W produced more (P ≦ 0.05) BW gain/hectare than RG alone or T. During yr 2, there were no differences (P ≥ 0.44) in ADG, BW gain/hectare, or grazing-days/hectare. In conclusion, the choice of cool-season annual to establish is highly weather-dependent, but R and W are generally superior to other small grains, and RG is a necessary complement to SG when interseeding cool-season annuals into Bermudagrass sod. [ABSTRACT FROM AUTHOR]

The experiment investigated the digestion of lipids from different forage silages in beef steers. Six Hereford × Friesian steers prepared with rumen and duodenal cannulas were given ad libitum access to a high-sugar grass silage, control grass silage, red clover silage, or mixtures of the red clover and each of the grass silages (50:50, DM basis). The experiment was conducted as an incomplete 5 × 5 Latin square, with an additional randomly repeated sequence. Total fatty acid and C18:3n-3 concentrations were greater (P < 0.05) for the high-sugar grass silage than the control grass silage or the red clover silage. Dry matter and total fatty acid intake were less (P < 0.05) for steers fed the control grass silage than for steers fed the other diets. Duodenal flow of C18:3n-3 was greater (P < 0.05), and flows of C 18:0 and total C 18:1 trans were less (P < 0.05), for the red clover silage compared with the 2 grass silage diets, with the mixtures intermediate. These results were supported by a reduction (P < 0.05) in biohydrogenation of C18:3n-3 for the red clover silage, with the mixtures again being intermediate. Flows of total branched- and odd-chain fatty acids were greater (P < 0.05) for the high-sugar grass silage diet, possibly as a result of greater microbial flow, because these fatty acids are associated with bacterial lipid. Duodenal flows of the chlorophyll metabolite, phytanic acid, were greater (P < 0.05) for animals fed the high-sugar grass silage treatments compared with the other treatments. These results confirm the potential for modifying the fatty acid composition of ruminant products by feeding red clover silage. [ABSTRACT FROM AUTHOR]

Two experiments were carried out to determine the effects of feeding grass silages differing in their water-soluble carbohydrate content, with or without red clover silage, on the efficiency of nutrient use. High-sugar grass, control grass, and red clover were ensiled in laboratory silos for use in an in vitro experiment (Exp. 1). For an in vivo experiment (Exp. 2), the same forage types were baled and ensiled. All silages were well preserved; within experiments the grass silages had similar composition, except for greater (P < 0.05) water-soluble carbohydrate concentrations in the high-sugar than the control grass silage. In Exp. 1, high-sugar grass, control grass, and red clover silages were fed alone or as mixtures (30:70, 50:50, or 70:30 on a DM basis, respectively) of each grass with the red clover silage to a simulated rumen culture system. There were no significant differences in microbial N flow or efficiency of microbial protein synthesis between individual forages. However, the corresponding values for the 70:30 ratio of high-sugar grass:red clover silage were greater (P < 0.05) than for the red clover silage. The value for the efficiency of N use (g of microbial N/g of feed N) was greater (0.86; P < 0.05) for high-sugar grass silage than the control grass silage. In addition, the high-sugar grass:red clover silage mixtures all gave greater (P < 0.05) values for the efficiency of N use than red clover silage alone; this difference was not achieved with the control grass mixture. Experiment 2 was an incomplete Latin square design conducted with 6 Hereford × Friesian steers (163 ± 5.9 kg of BW) with rumen and duodenal cannulas fed the following 5 silage diets: high-sugar grass silage; control grass silage; high-sugar grass and red clover silage (50:50 DM basis); control grass and red clover silage (50:50 DM basis); and red clover silage. Rumen NH3-N concentration was lowest (P < 0.05) with the high-sugar grass silage. Microbial N flows to the duodenum and efficiency of microbial protein synthesis were greater (P < 0.05) for steers fed the high-sugar grass silage than for control grass and red clover silages, and mixing red clover with grass silages increased (P < 0.05) these values compared with red clover silage alone. In both experiments, the efficiency of incorporation of silage N into microbial N was more than 20% greater (P < 0.05) for high-sugar grass than for control grass silage. These data suggest that grass silage with high-sugar content provides a forage-based strategy for balancing N and energy supply and improving the efficiency of use of grass silage N in the rumen. [ABSTRACT FROM AUTHOR]

Targhee x Hampshire lambs (average BW 24 ± 1 kg) were used to determine the effect of finishing on concentrate or by grazing ryegrass forage on slaughter weights of 52 kg (N) or 77 kg (H) on tissue accretion and lamb wholesale cutout. When fed to similar slaughter weights, the wholesale cuts of concentrate-fed lambs were heavier (P < 0.05) than the same cuts from forage-fed lambs; however, when expressed as a percentage of side weight, carcasses of forage-fed lambs had a higher (P < 0.001) percentage of leg than concentrate-fed lambs. Increasing slaughter weight from 52 to 77 kg resulted in a 1-kg increase in loin weight for lambs finished on concentrate and a 0.60-kg increase for lambs finished on forage (diet x slaughter weight, P < 0.03); however, the increased loin weight for lambs finished on concentrate was due largely to increased fat deposition. For lambs slaughtered at 77 kg, those finished on forage had more lean mass in the leg, loin, rack, and shoulder than those finished on concentrate, but lean mass in these cuts did not differ between diets for lambs slaughtered at 52 kg (diet x slaughter weight, P < 0.01). At the normal slaughter weight (52 kg), concentrate-fed lambs had 50% more dissectible fat than forage-fed lambs, whereas at the heavy slaughter weight, a 79% greater amount of dissectible fat was observed for concentrate- vs. forage-fed lambs (diet x slaughter weight, P < 0.001). Lean and fat accretion rates were higher (P < 0.001) for concentrate-fed lambs than for forage-fed lambs. The lean-to- fat ratio of forage-fed lambs was higher (P < 0.001) than that of concentrate-fed lambs; however, forage finishing decreased accretion rates of all tissues compared with concentrate feeding, and these differences between forage and concentrate feeding were magnified at heavier slaughter weights. [ABSTRACT FROM AUTHOR]

Our objective was to determine the effect of the duration of grazing before slaughter on the fatty acid composition of muscle fat and s.c. adipose tissue (SAT) of beef heifers. Sixty crossbred Charolais heifers (n = 15 per treatment) were assigned randomly to one of four dietary treatments: 45 animals (Treatments 1, 2, and 3, respectively) were housed at the beginning of the experiment, and 15 (Treatment 4) were fed at pasture. Two groups of 15 heifers were moved to pasture 40 d (Treatment 2) and 99 d (Treatment 3) before slaughter, respectively, resulting in preslaughter grazing periods of 0, 40, 99, or 158 d for Treatments 1, 2, 3, and 4, respectively. Before grazing the predominantly perennial ryegrass pasture, animals were housed and offered grass silage ad libitum and 3 kg of concentrate diet (650 g of grass silage/kg of total DMI). After slaughter, the fatty acid profile of the neutral (NL) and polar lipid (PL) fractions of muscle fat from the LM and the total lipids from SAT were analyzed by gas chromatography. Duration of grazing showed a quadratic tendency on mean carcass weight (P = 0.08), but did not affect growth (P = 0.27) or the lipid content (P = 0.13) of the LM. Increasing the duration of grazing led to a linear increase (P < 0.001) in the concentration (on fresh-tissue basis) of CLA in muscle fat (from 11.80 to 17.75 mg/100 g of muscle in NL, and from 0.52 to 0.82 mg/100 of g muscle in PL) and in SAT (from 3.98 to 10.23 mg/g of SAT; P < 0.001), and increased the concentration of C18:1trans-11 in both muscle fat fractions (P < 0.001) and in SAT (P < 0.001). In the total muscle lipids, the polyunsaturated to saturated fatty acid ratio (P:S) increased from 0.12 to 0.15 with increased duration of grazing following a linear (P < 0.05) and cubic pattern (P < 0.05). Increasing the duration of grazing led to a linear decrease in the n-6:n-3 ratio of muscle fat from 2.00 to 1.32 (P < 0.001), and from 2.64 to 1.65 in the SAT lipids (P < 0.001), mainly as a consequence of the increased concentration of C18:3n3. It is concluded that muscle fat and SAT fatty acid profile was improved from a human health perspective by pasture feeding, and that this improvement depended on the duration of grazing. [ABSTRACT FROM AUTHOR]

The objectives of this study were to determine the effects of finishing lambs on concentrate (C) or by grazing ryegrass forage (F) to slaughter end weights of 52 (N) or 77 kg (H) on carcass characteristics and organoleptic properties. This experiment included 64 Targhee × Hampshire lambs (average BW = 24 ± 1 kg) in a 2 × 2 × 2 factorial arrangement of treatments to compare wethers vs. ewes, C vs. F, and N vs. H slaughter weights. No interactions (P > 0.10) were ob served between gender and other main effects. Hot carcass weight and dressing percent were greater (P < 0.001) for C-than for F-fed lambs. Backfat thickness also was greater (P < 0.001) for lambs fed C than for those fed F. Moreover, USDA lean quality score and USDA yield grades were higher (P < 0.001) for C than for F-fed lambs, as well as for lambs slaughtered at H vs. N market weights. There was a higher (P < 0.005) incidence of off odors and off flavors in cooked muscle from F- vs. C-fed lambs, and also from H vs. N slaughter-weight lambs. The heavy C-fed lambs had juicier (P < 0.001) meat than other treatment combinations. Cooked meat from C-fed lambs received higher (P < 0.001) overall acceptability scores. Concentrate-finished lambs produced fatter carcasses and more palatable meat than forage finished lambs; however, forage finishing allowed for slaughter at heavier weights without excessive fat deposition. [ABSTRACT FROM AUTHOR]

The objective of this study was to determine the effect of type of conserved forage and concentrate composition on the quality of beef held in overwrapped (aerobic) or modified atmosphere packaging under simulated retail display for 17 d. Friesian steers (n = 45) were assigned randomly to one of five dietary treatments: 1) extensively fermented grass silage plus silage concentrate (EFS); 2) restricted fermented grass silage plus silage concentrate (RFS); 3) starch-based concentrate plus wheat straw (SC); 4) nonstarch-based concentrate plus wheat straw (NSC); or 5) zero-grazed perennial ryegrass plus grass concentrate (RYE). Meat quality was determined by measuring color, lipid oxidation (TBARS), α-tocopherol concentrations, and fatty acid composition. In aerobically packaged beef, there was a display x diet interactive effect (P < 0.001) on Hunter a* values, with steaks from the EFS group haying higher (P < 0.05) a* values than all other dietary groups from d 6 through d 17. Moreover, during the last 12 d of display, beef from the EFS group had the lowest (P < 0.01) proportion of metmyoglobin (display day × diet; P < 0.001). Under aerobic packaging, the SC and NSC groups produced steaks with higher (P < 0.05) TBARS values than RFS, EFS, and RYE groups, which did not differ from each other (display day × diet; P < 0.01). The SC and NSC groups had higher (P < 0.05) oxidation levels than RFS, EFS, and RYE groups, which did not differ from each other. Beef from the EFS group had (P < 0.05) higher concentrations of α-tocopherol than from the SC, NSC, and RYE groups. Beef from EFS-fed steers had a higher (P < 0.05) proportion of saturated fatty acids than the SC and NSC groups. It was concluded that the method of grass conservation influenced beef color, whereas concentrate composition did not. Color of aerobically packaged beef was improved by feeding animals silage that had undergone extensive fermentation. Conversely, oxidative stability was decreased by feeding animals starch- and nonstarch-based concentrate diets. [ABSTRACT FROM AUTHOR]

Two experiments were conducted to evaluate perennial regrass straw as a forage source for ruminants. Experiment i evaluated digestion and physiological variables in steers offered perennial ryegrass straw containing increasing levels of ergot alkaloid, lolitrem B. Sixteen ruminally cannulated Angus x Hereford steers (231 ± 2 kg BW) were blocked by weight and assigned randomly to one of four treatments. Steers were provided perennial ryegrass straw at 120% of the previous 5-d average intake. Before straw feeding, soybean meal was provided (0.1% BW; CP basis) to meet the estimated requirement for degradable intake protein. Low (L) and high (H) lolitrem B straws (<100 and 1,550 ppb, respectively; DM basis) were used to formulate treatment diets: 100% L; 67% L:33% H; 33% L:67% H; 100% H (DM basis). Intake and digestibility of DM and OM, and ruminal pH, total VFA, and NH3-N were not affected by increasing lolitrem B concentration. Ruminal indigestible ADF (IADF) fill increased linearly (P = 0.01) and IADF passage rate decreased linearly (P = 0.04) as lolitrem B increased. Experiment 2 evaluated performance and production by 72 Angus × Hereford cows (539 ± 5 kg BW) consuming perennial ryegrass straw containing increasing lolitrem B during the last third of gestation. Cows were blocked by body condition score and randomly assigned to one of three treatments. Cows were provided perennial ryegrass straw ad libitum and supplemented with soybean meal (0.1% BW; CP basis) to meet the estimated requirement for degradable intake protein. Mixtures of a L and H lolitrem B straw (467 and 2,017 ppb, respectively) were used to formulate treatment diets: 100% L, 50% L:50% H, 100% H (DM basis). Thirteen of 24 cows on the 100% H treatment exhibited signs of ryegrass staggers and were removed from the study; nevertheless, lolitrem B concentration did not influence pre- or postcalving weight or body condition score change. These data suggest that feeding perennial ryegrass straw containing up to 1,550 ppb lolitrem B (DM basis) did not adversely affect nutrient digestion or physiological response variables in steers. However, providing straw with a lolitrem B concentration of approximately 2,000 ppb (DM basis) resulted in 54% of cows exhibiting signs of ryegrass staggers. These data suggest that blending straws with a high (>2,000 ppb) and low (<500 ppb) concentration of lolitrem B can be a successful management practice. [ABSTRACT FROM AUTHOR]

Splanchnic metabolism of nitrogenous nutrients and their uptake by the hind limb were studied in finishing lambs receiving ryegrass harvested at grazing stage with or without barley supplementation. Six multicatheterized lambs (40.2 ± 1.5 kg) were fed with frozen ryegrass (RG) at 690 kJ of ME intake (MEI)·d[sup -1]·BW[sup -0.75] and 20.8 g of N intake (NI)/d successively without and with barley supplementation (RG + B), according to a crossover design. Barley supplementation represented 21% of DM intake and increased the MEI and the NI by 32 and 24% respectively, (P < 0.01). In the ruminal fluid, barley increased acetate and butyrate concentrations by 21.2 and 49.6%, respectively (P < 0.04), without any effect on the ammonia concentration. Consequently, the net portal appearance (NPA) of ammonia was not modified, but the NPA of total amino acids (TAA; +38%) and nonessential amino acids (NEAA; +45%) was increased (P < 0.05) by barley supplementation. Taken individually, the NPA of the essential amino acids (EAA) was increased for isoleucine (+32%; P < 0.05), threonine (+151%; P < 0.03), and lysine (+26%; P < 0.06), with no effect for the other EAA. In contrast to what was observed at the PDV level, no significant alteration in the net hepatic amino acid flux was observed for TAA, EAA, NEAA, branched-chain amino acids (BCAA), urea, and ammonia after barley supplementation, showing a relatively minor role of the liver in the regulation of the supply of amino acids to the peripheral tissues. However, taken individually, the net hepatic uptake of some NEAA involved in gluconeogenesis and/or ureagenesis was altered with barley supplementation: the alanine uptake was increased by 44% (P < 0.05), aspartate + asparagine (asx) uptake was decreased by 18% (P < 0.01), and glutamate + glutamine (glx) release tended (P < 0.10) to be increased by 208%. With barley supplementation, NI increased by 5 g of N/d, and net splanchnic release increased by 4.63 g of N/d. Consequently, the additional dietary N supply (together with energy supply) was nearly exclusively available to peripheral tissues as AA-N (N as amino acids), but no strong effect of this additional supply of AA to the hind limb could be demonstrated in terms of net AA hind limb fluxes. Consequently, barley supplementation of a ryegrass-based diet increased the net AA release by the splanchnic tissues, with little effect on the AA net uptake by the peripheral tissues. [ABSTRACT FROM AUTHOR]

The objective of this study was to evaluate the concentrate supplementation frequency effects on forage characteristics and performance of early-weaned beef calves grazing annual ryegrass (Lolium multiflorum). The experiments were conducted in Ona, FL from February to April (Exp. 1) and June (Exp. 2) 2019 and 2020. In Exp. 1, thirty-two early-weaned calves (82±12 d of age) were allocated to 8 annual ryegrass pastures (4 calves/pasture) and supplemented with 1% BW. Treatments were 2 concentrate supplementation frequencies, daily (DAILY) or three times per week (3X; Monday, Wednesday, and Friday) distributed in a randomized complete block design with 4 replicates. Calves receiving the 3X treatment had the daily supplement level multiplied by 7 d and divided by 3 feeding days. Pastures (experimental units; 0.4 ha/pasture) were grazed with a continuous and fixed stocking rate. There was no difference in herbage mass (P = 0.85; mean = 3050 kg/ha), herbage allowance (P = 0.91; mean = 3.0 kg DM/kg BW), CP (P = 0.88; mean = 17.5%), and in vitro digestible organic matter (P = 0.82; mean = 74%). In addition, there was no difference in ADG (P = 0.60, mean = 0.65 kg/d), plasma urea nitrogen (P = 0.88; mean = 10 mg/dL), and glucose (P = 0.45; mean = 72 mg/dL). In Exp. 2, twenty early-weaned calves from Exp. 1 were maintained in the same treatment and placed in a drylot with individual stall for forage DM intake, total DM intake, and in vivo digestibility measurements. Treatments were the same described in Exp. 1 distributed in a randomized complete block design with 10 replicates. Calves receiving the DAILY treatment had greater forage DM intake (P = 0.02; 1.8 vs. 1.6% BW), total DM intake (P < 0.01; 2.7 vs. 2.5% BW), and in vivo digestibility (P < 0.01; 87 vs. 85%) than 3X. Feeding three times per week may be a feasible management practice to decrease the cost of labor related to feeding early-weaned beef calves. [ABSTRACT FROM AUTHOR]

Presents a study designed to compare Marshall and Surrey ryegrass with continuous and rotational grazing. Formulation of feeds; Relocation of grazed steers; Analysis using General Linear Model procedure; Information on canopy height and forage mass; Rotation of steers out of a paddock.

The objective of this study was to determine the effect on digestibility of forages using a daisy jar system with inoculum from steers supplemented with the yeast fermentation product Saccharomyces cerevisiae. Forages tested included ryegrass, wheat, orchard grass, alfalfa, and sorghum sudan hays. Samples were ground through a 1mm screen, placed in Ankom F57 bags, and run in triplicate to increase statistical significance. Two ruminally cannulated jersey steers were used in a switchback design. Animals were housed in a dry lot pen. The study consisted of 2 three-week periods, 2-week standardization followed by a 1-week test period. Diets offered for period 1 were steer A = 100% alfalfa hay w/o yeast product and steer B = 100% wheat hay w/o yeast product. Diets offered for period 2 were steer A =100% alfalfa hay +15g/h/d yeast product and steer B =100% wheat hay +15g/h/d yeast product. During the test week, rumen fluid contents were collected from each donor via rumen cannula approximately 4 h after feeding and taken to the lab to be composited. The samples were incubated for 0 h, 24 h, 48 h, 72 h, and 96 h. At the end of the incubation period bags were collected and cold shocked to stop microbial digestion. Samples were dried at 55oC and stored for later analysis. Model included trt (+/-yeast), forage, hr, and interactions forage*hr and forage*trt. No significant differences were observed (P = 0.38) on DM digestibility or NDF digestibility (P = 0.76) with the supplementation of yeast fermentation product. Forage*Trt was significant (P = 0.03 DMdig, P = 0.02 NDFdig). Implications of this study are the inclusion of a Saccharomyces cerevisiae fermentation product at a rate of 15g/h/d may not impact overall forage NDF or DM digestibility but may impact types of forage differently in an in vitro system using composited inoculum from donors on a forage diet. [ABSTRACT FROM AUTHOR]

The purpose of this study was to determine if supplementation of a yeast fermentation product had an effect on the ADG, performance, and meat quality characteristics of Kathadin sheep fed a ryegrass hay based diet in drylot. Twenty-four Katahdin lambs were divided into two groups (male, n = 8; female n = 16) based on weight and gender: a control (CON) and treatment (TRT) used in a repeated block design. The lambs had a BW of 21.5 ± 2.5 kg, and concluded with a finishing weight of 36.3 ± 3.4 kg. Lambs were housed on dirt drylot with shade structures, and offered an ad libitum TMR diet was formulated to be isocaloric and isonitrogenous at 14% CP and was ryegrass hay based, and top dressed with ground corn as a carrier. The TRT received the yeast supplement at a rate of 4/g/h/d. The diet was offered at 2% of the group's body weight ad libitum. A 1-wk standardization period was conducted before the start of the study to obtain a 5% refusal rate. Orts were collected and recorded, as well as weekly feed samples were collected twice a week, and compiled for a chemical analysis for NDF, ADF, ASH, CP, and ether extract. Temperature and humidity data was also collected throughout the study. Lambs were weighed weekly with a rolling weight being used for the ADG of the lambs. Proc mixed procedures of SAS was used for data analysis. We found no statistical significance in DMI (CON=11.14 ±3.36 kg/d and TRT= 10.89 ±3.55 kg/d per group), and no statistical significance by gender (P < 0.11). There was a statistical significance (P < 0.03), for ADG per group. This suggests that there is a tendency for greater performance and ADG for lambs supplemented with a yeast fermentation product. [ABSTRACT FROM AUTHOR]

Interest in the use of yeast fermentation products has grown in recent years as a natural feed additive for the growth of ruminants in a feedlot setting. The purpose of this study was to determine if the supplementation of a Saccharomyces cerevisiae fermentation product (SCFP) had an effect on apparent digestibility in Katahdin lambs offered an annual ryegrass hay-based finishing diet. Six Katahdin wethers (n = 6) were divided into two groups CON and TRT and placed into individual metabolism crates in a temperature-controlled room, (21.1° C), and fitted with fecal collection bags. Lambs were offered a TMR diet that was formulated to be isocaloric and isonitrogenous at 14% CP, and annual ryegrass hay based with a top dress of ground corn to be used as a carrier. The TRT received the yeast supplement at a rate of 4g/head/day. The diet was offered ad libitum with orts collected daily to maintain a 5% refusal rate. Lambs were housed in the metabolism crates for 1-wk before the start of the study for adjustment, followed by 4 days of data collection. Feed, orts, fecal, and urine samples were collected and recorded daily during the collection period for each wether and compiled by animal for chemical analysis of DM, NDF, ADF, CP, and ether extract. Indigestible ADF was used as a digestibility marker to determine apparent digestibility. Data were analyzed by PROC GLM for statistical significance. There was no statistical significance found for apparent digestibility of DM (CON=64.6 ±2.5; TRT=63.4±2.5), CP (CON=65.0 ±2.1; TRT=65.9±2.1), NDF (CON=41.2±1.9; TRT=43.0±1.9), or ADF (CON=26.1 ±4.7; TRT=33.8±4.7) between the two groups (P > 0.05). This study concluded that the supplementation of a SCFP had no significant effect on the apparent digestibility of Katahdin wether lambs that were offered an annual ryegrass hay-based finishing diet. [ABSTRACT FROM AUTHOR]

Annual ryegrass (Lolium multiflorum Lam.) can be divided into two cytotypes: diploid (2n = 2x) and tetraploid (2n = 4x). Polyploid versions of a given plant species result in increased seedling vigor, more robust growth and, potentially, greater yield. While most data suggest no difference in yield between diploid and tetraploid cultivars, there is still potential for weight gain advantages thanks to increased non-structural carbohydrates in tetraploid cells. The objectives of this study were to compare weight gain of cattle grazing either diploid or tetraploid cultivars of annual ryegrass. Two diploid annual ryegrass cultivars (Marshall and Tam 90) and two tetraploid cultivars (Jumbo and Nelson) were planted in 0.81-ha pastures, each replicated four times. Four steers (mean initial BW = 214 kg) were randomly assigned to each pasture for an 82-d grazing period. Body weights were recorded starting at day 0 then every 28 days throughout the season. Data were analyzed in the GLM procedure of SAS using a significance level of α = 0.05. There were significant differences between cytotypes with respect to seasonal yield with diploids (9547.90 kg/ha) yielding greater than tetraploids (7762.00 kg/ha). As expected, ADF and NDF fractions were significantly less for tetraploids (ADF; 31.39%, NDF; 31.39%) compared to diploids (ADF; 33.75%, NDF; 53.25%). Tetraploids also contained significantly greater crude protein (13.50%) than diploids (12.90%). Cytotype had no effect on final average daily gain (ADG) (P = 0.9427). However, final ADG was significantly impacted by cultivar (P = 0.0134). Final ADG for Tam 90 (1.10 kg/d) was greater than Marshall (0.92 kg/d). Cattle grazing Nelson (1.04 kg/d) and Jumbo (0.99 kg/d) did not differ. Results show that regardless of differences in seasonal yield and nutritive value between cytotypes, there were no advantages in ADG for cattle grazing either cytotype. [ABSTRACT FROM AUTHOR]

Annual ryegrass (Lolium multiflorum Lam.) can be divided into two cytotypes: diploid (2n = 2x) and tetraploid (2n = 4x). Polyploid versions of a given plant species result in increased seedling vigor, more robust growth and, potentially, greater yield. While most data suggest no difference in yield between diploid and tetraploid cultivars, there is still potential for weight gain advantages thanks to increased non-structural carbohydrates in tetraploid cells. The objectives of this study were to compare weight gain of cattle grazing either diploid or tetraploid cultivars of annual ryegrass. Two diploid annual ryegrass cultivars (Marshall and Tam 90) and two tetraploid cultivars (Jumbo and Nelson) were planted in 0.81-ha pastures, each replicated four times. Four steers (mean initial BW = 214 kg) were randomly assigned to each pasture for an 82-d grazing period. Body weights were recorded starting at d0 then every 28 days throughout the season. Data were analyzed in the GLM procedure of SAS using a significance level of α = 0.05. There were significant differences between cytotypes with respect to seasonal yield with diploids (9547.90 kg/ha) yielding greater than tetraploids (7762.00 kg/ha). As expected, ADF and NDF fractions were significantly less for tetraploids (ADF; 31.39%, NDF; 31.39%) compared to diploids (ADF; 33.75%, NDF; 53.25%). Tetraploids also contained significantly greater crude protein (13.50%) than diploids (12.90%). Cytotype had no effect on final average daily gain (ADG) (P = 0.9427). However, final ADG was significantly impacted by cultivar (P = 0.0134). Final ADG for Tam 90 (1.10 kg/d) was greater than Marshall (0.92 kg/d). Cattle grazing Nelson (1.04 kg/d) and Jumbo (0.99 kg/d) did not differ. Results show that regardless of differences in seasonal yield and nutritive value between cytotypes, there were no advantages in ADG for cattle grazing either cytotype. [ABSTRACT FROM AUTHOR]

The objective of this experiment was to determine appropriate methods for estimating fecal output, digestibility, and intake in red deer (Cervus elaphus). Dry matter intake (DMI), digestibility, and fecal output were estimated using the dual-marker (titanium dioxide; TiO 2 and indigestible acid detergent fiber) technique, double n -alkane ratio technique (ALK) and the pulse dose (Yttrium; Y) technique to determine a suitable method to estimate DMI, fecal output, and digestibility measurements. Four male and four female deer were stratified by sex and randomly assigned either fresh-cut perennial ryegrass (Lolium perenne L.) or fresh-cut plantain (Plantago lanceolata) ad libitum in a cross-over design experiment. Actual DMI (mean ± SD: 1.5 ± 0.36 kg DM/d), digestibility (0.70 ± 0.06), and fecal output (0.45 ± 0.1 kg DM/d) were measured daily over the collection periods, and the average of each period was used for methods' comparison. The ALK method adequately estimated digestibility and fecal output of plantain; however, overestimated digestibility (P < 0.05) and DMI of ryegrass, so that there was no statistical agreement (P > 0.10) in DMI when diets were pooled. The overestimated DMI of the ryegrass diet led to ALK predicting greater intake when deer consumed ryegrass than plantain, which was the opposite of actual measurements. The pulse dosed Y overestimated (P < 0.05) fecal output and consequently DMI for both plantain and ryegrass, however, indicated similar trends to actual values. The dual-marker technique using TiO2 was able to detect the statistical differences between plantain and ryegrass as the actual measurements, had moderate to strong precision (r = 0.50 to 0.66) and statistical agreement (P < 0.05) with the pooled diet data. Therefore, the dual-marker technique provided the best alternative estimation method to actual measurements of forage DMI of grazing red deer. [ABSTRACT FROM AUTHOR]

Presents abstracts of studies on ruminant production and forages published in the January 2001 issue of the `Journal of Animal Science.' `Coastal and Tifton 85 Spring Recovery Following Ryegrass Sod-Seeding,' by G.M. Hill et al.; `Stocker Lamb Preference for Cool Season Grass Hay Harvested in the Afternoon,' by L.A. Richards et al.; `Intake of Coastal and Tifton 85 Bermudagrass Hays by Beef Cows,' by G.M. Hill et al.

The purpose of this study was to determine if supplementation of a yeast fermentation product had an effect on the ADG, performance, and meat quality characteristics of Katahdin sheep fed a ryegrass hay based diet in drylot. Twenty-four Katahdin lambs were divided into two groups (male, n = 8; female n = 16) based on weight and gender: a control (CON) and treatment (TRT) used in a repeated block design. The lambs had a BW of 21.5 ± 2.5 kg, and concluded with a finishing weight of 36.3 ± 3.4 kg. Lambs were housed on dirt drylot with shade structures, and offered an ad libitum TMR diet was formulated to be isocaloric and isonitrogenous at 14% CP and was ryegrass hay based, and top dressed with ground corn as a carrier. The TRT received the yeast supplement at a rate of 4/g/h/d. The diet was offered at 2% of the group's body weight ad libitum. A 1-wk standardization period was conducted before the start of the study to obtain a 5% refusal rate. Orts were collected and recorded, as well as weekly feed samples were collected twice a week, and compiled for a chemical analysis for NDF, ADF, ASH, CP, and ether extract. Temperature and humidity data was also collected throughout the study. Lambs were weighed weekly with a rolling weight being used for the ADG of the lambs. Proc mixed procedures of SAS was used for data analysis. We found no statistical significance in DMI (CON=11.14 ±3.36 kg/d and TRT= 10.89 ±3.55 kg/d per group), and no statistical significance by gender (P < 0.11). There was a statistical significance (P < 0.03), for ADG per group. This suggests that there is a tendency for greater performance and ADG for lambs supplemented with a yeast fermentation product. [ABSTRACT FROM AUTHOR]

Three groups of calf-fed steers were used to evaluate the effects of control (100% concentrate), Italian rye grass (IRG) silage (ad libitum with 66% concentrate), and IRG hay (ad libitum with 66% concentrate) on adipogenic gene expression in longissimus thoracis (LT) muscle. Eight randomly selected Hanwoo steer from each group were fed with a 3-step diet, which were calf diet (6 to 11 mo), early fattening diet (12 to 20 mo), and final fattening diet (21 to 30 mo). One gram of muscle biopsy samples was taken from cattle on 7, 12, 24, and 30 mo on both sides of the LT area. Real-time PCR determined the levels of adipogenic marker (C/EBPb, PPARγ, SCD, and GPR43) and myogenic marker (Pax3, Myf5, myogenin, GLUT4, MHC I, MHC IIA, and MHC IIX) mRNA. Data were analyzed as a completely randomized design using the MIXED model, and each treatment was performed in triplicate. Means were considered different at P < 0.05. Average daily gain at calf and early fattening period of study were not different, but final fattening period of the study was lower in the IRG hay group (P < 0.05) than in control steers. Back fat thickness, rib eye area, and carcass weight of the control group were greater than those of the IRG diet group (P < 0.05). However, marbling score and shear force (kg/0.5 in²) were not different among the control and IRG diets. Relative PPARγ and SCD mRNA levels in biopsy samples were increased (P < 0.05) on the days of fattening diet, but relative C/EBPb mRNA level was decreased (P < 0.05). The level of Pax3, Myf5, and myogenin were decreased on the days of fattening diet (P < 0.05). Relative MHC IIX mRNA levels were greater (P < 0.05) in 12-mo-old Hanwoo steer than in control steers. Italian rye grass hay group cattle had greater MHC IIX mRNA levels than the other groups (P < 0.05). These data indicate that relative mRNA levels of adipogenic genes in LT muscle are decreased during the days of high-roughage diet (IRG silage and hay). The high-roughage diet also decreased back fat thickness and rib eye area but not affect marbling score. [ABSTRACT FROM AUTHOR]

The objective of this study was to establish the influence of daily herbage allowance and concentrate supplementation on the milk production performance of spring calving dairy cows in early lactation. Sixty-six (30 primiparous and 36 multiparous) Holstein Friesian dairy cows (mean calving date 7 Feb) were randomly assigned to a 6 treatment (n=11) grazing study. The treatment groups were comprised of 3 DHA's (13, 16 and 19 kg DM/cow/day >4 cm) and 2 concentrate supplementation levels (0 and 4 kg DM/day). Treatments were imposed from 21 February to 8 May (11 weeks). Milk yield was recorded daily; milk composition and liveweight were determined weekly. All animal parameters were analysed using covariate analysis within a completely randomised statistical design. Offering a low DHA in early lactation resulted in only a slight reduction in milk yield and liveweight. The inclusion of concentrate in the diet increased (P<0.001) milk yield, milk composition and liveweight. These results indicate that as DHA increases, the rate of increase in milk production declined. Including concentrate in the diet resulted in increased milk production and liveweight. [ABSTRACT FROM AUTHOR]

To study the influence of silage inoculant SilAll4x4 (Alltech, Lexington. KY) on the fermentation process in grass silages and on the nutritive value of the produced silages, an experiment with lab silos using perennial ryegrass was carried out. In May and September 2004, good quality grass was harvested and wilted to DM concentrations of 20, 35 and 50%. Wilted grass was cut and ensiled in 1-l Weck jars with or without SilAll4x4 (10 mg per kg of grass). After 3, 14, 28 and 90 days of ensiling, at least two jars per treatment were opened and analyzed for DM, ash, fermentation products (lactic acid, VFA , ammonia), and microbiological composition (lactic acid bacteria, entero bacteria, yeasts and moulds). After 90 days, samples were also incubated in rumen fluid and gas production was measured in time to determine the rate of OM degradation. At maximum rate of gas production the amount of purines in each vial was analyzed as a parameter for microbial biomass. The inoculated silages started with 10 times more LAB than the control silages which resulted in a faster pH drop and faster formation of lactic acid. Inoculated silages reached a stable pH value of 3.8 to 4.2 between day 14 and 28; control silages reached a stable pH value of 4.2 to 4.6 after 28 days. The faster decline of pH in the inoculated silages resulted in a faster drop of entero bacteria. The levels of ammonia were significantly lower in inoculated silages. The insoluble nitrogen fraction was slightly (P > 0.05) higher in inoculated silages. The differences between inoculated and control silages were more pronounced in the high DM silages. Yeasts and moulds were detected at ensiling, but numbers were below detections levels after 90 days with no effect of inoculation. At maximum fermentation rate, amounts of purines in the incubation vials were higher for inoculated silages (18.8 versus 17.7 RNA-equivalents per g of OM for Control; P = 0.02). This suggests that inoculation with SilAll4x4 resulted in a better protein quality of the silage, which influences the efficiency of rumen microbial protein synthesis. [ABSTRACT FROM AUTHOR]

A different degradability of starch sources may influence rumen fermentation and consequently milk production. In a 3 × 3 Latin square design experiment with 12 cows (6 rumen-cannulated) grazing ryegrass/clover pasture, the effect of three supplements, differing in their ruminal starch availability, on milk production, blood metabolites and rumen pH fluctuation was determined. From a milk production of 21 kg/d on, cows received the same amount of net energy for lactation (3.9 MJ NEL) per kg additionally produced milk as ground barley (B), barley/corn (B/C) or corn (C). Each experimental period lasted for 28 d with data collection from d 21 to 28. Grass intake was quantified by the double alkane technique using controlled-release capsules. Milk yield and milk constituents were recorded for each milking. Rumen pH was measured continuously for 22 h/d with a pH electrode placed in the rumen through the cannula. For each cow pH data were summarized as mean, maximum and minimum pH and time period when pH was <5.8 and <6.2. Venous blood was sampled on d 21 and 27 of each experimental period. Cows of treatment B (4.0 kg dry matter (DM)/d) were allocated more supplement (P < 0.1) than cows of treatment B/C (3.6 kg DM/d) and C (3.4 kg DM/d). However, total intake of DM and NEL were not affected by treatments. Milk yield and milk fat content did not differ among treatment groups whereas the milk protein content was higher for group B compared to group C (P < 0.05). While the concentration of milk urea nitrogen was higher (P < 0.05) for cows fed B/C than for cows fed B or C, the plasma urea concentration was highest in groups B/C and B and lower (P < 0.05) in group C. The type of supplement had no influence on mean (6.17), maximum (6.56), and minimum (5.73) rumen pH and time when the pH was <5.8 (88 min/d) or <6.2 (676 min/d). In conclusion, the starch source provided by the supplement had an effect on nitrogen use efficiency in dairy cows whereas the influence on rumen pH was low. However regardless of treatment, the time when the pH was <6.2 was quite long which might compromise rumen microbial activity. [ABSTRACT FROM AUTHOR]

Level of supplement (SUP) has various associative effects on forage intake, total diet, and performance per animal and unit land area. The objective of this study was to quantify ADG and gain/ha of stockers grazing a mixture of 'Maton' rye and 'TAM-90' of annual ryegrass at 3 stocking rates (STK) and receiving 3 levels of SUP. Stocking rates in a fixed stocking design with two pasture replicates per treatment were 3.7, 5.2, and 7.2 hd/ha based on initial stocker weights of 270 kg/animal (half-Simmental steers and heifers). A ration containing 98% cracked corn plus Rumensin 80, salt, dicalcium phosphate, and dried molasses was group fed daily at 0 (PAS), 0.4% BW (.4BW), and 0.8% BW (.8BW). Stocking was continuous from Dec. 20 to May 17 (148 d). Average daily gain was greatest (P<.01) at 1.5 kg/d from .8 BW, and similar for 0.4 BW and PAS at 1.28 and 1.15 kg/d, respectively. The ADG were similar for calves stocked at 3.7 and 5.2 hd/d, 1.37 and 1.47 kg/d respectively, and both were higher (P<.01) than ADG of 1.05 kg/d at the highest STK of 7.2 hd/ha. The ADG among the nine treatments ranged from 0.51 kg/d from PAS when stocked at 7.2 hd/ha to 1.5 kg/d from .8 BW when stocked at 3.7 hd/ha. The .4 BW SUP level was more efficient (P<.01) at each STK compared to cattle receiving .8 BW. The SUP:extra gain ratios for .4 BW were 4.7:1, 5.4:1, and 10.6:1 when stocked at 7.2, 5.2, and 3.7 hd/ha, respectively; whereas, ratios for .8 BW were 7.2:1, 7.8:1, and 15.9:1, respectively, when stocked at 7.2, 5.2, and 3.7 hd/ha. Gain per animal efficiencies of SUP were maximized at .4 BW at both high and medium stocking rates, and were minimized at .8 BW and low stocking rate. Gain per ha of 543 kg was least on PAS and 7.2 hd/ha, and greatest from .8 BW and medium stocking rate (5.2 hd/ha) at 1083 kg/ha (P<.01). Management strategies for stocking rate and supplementation are uniquely linked to animal weight, animal prices, pasture and supplement costs, ADG, and selling margin. [ABSTRACT FROM AUTHOR]

Four Holstein heifers (360 BW) fltted with ruminal trocars were used in a 4x4 Latin square design to evaluate the effects of no extract (CTR), 30 g/d of alfalfa extract (AEX; 10% malate, and 1.5% saponins), a mixture of 180 mg/d of cinnamaldehyde and 90 mg/d of eugenol (CIE), and the combination of the two treatments (MIX) on rumen fermentation. Heifers were fed a 10:90 straw to concentrate ratio diet. Each period consisted of 15 d for adaptation and 6 d for sampling. On d 16, 17 and 18 of each period, DM and water intake were measured. On d 19, 20 and 21 ruminal content was sampled at 0, 3, 6, 9, and 12 h after feeding to determine ruminal pH and the concentrations of volatile fatty acids (VFA), L-lactate, large peptides (LPep), small peptides plus AA (SPep+AA), and ammonia N. On d 20 and 21, samples of rumen fluid were also taken at 0 and 3 h after feeding to determine protozoa counts. On the last day, rumen fluid was used to determine in vitro DM and CP degradation of alfalfa hay (AH), ryegrass hay, barley grain, wheat grain, corn grain (CG) and soybean meal (SBM) after 4 and 24 h incubation. Relative to CTR, CIE and AEX reduced (P<0.05) DM and water intake, and Entodiniomorphs counts, but did not affect pH, total VFA concentration, propionate and butyrate proportions, and LPep N concentration. The CIE tended (P=0.08) to reduce ammonia N, and to increase SPep+AA N concentrations. The AEX increased (P<0.05) the acetate to propionate ratio and reduced (P<0.05) Entodiniomorphs counts. The MIX tended (P=0.06) to reduce DM intake, water intake and ruminal pH. In vitro, CIE and MIX reduced (P<0.05) CP degradation of SBM and CG, and MIX also reduced (P<0.05) CP degradation of AH at 4 h after incubation, but all differences disappeared after 24 h of incubation. Results suggest that CIE and AEX had some effects on DM intake and rumen fermentation, but the effects of their combination were not additive. [ABSTRACT FROM AUTHOR]

Four fattening Holstein heifers (450 kg BW) fltted with ruminal trocars and fed a 10:90 straw to concentrate ratio diet were used in a 4x4 Latin square design to evaluate the effects of no extract (CTR), 2 g/d of anise oil (ANI; 10% of anethole), 1 g/d of capsicum extract (CAP; 15% of capsaicin), and a mixture of 0.6 g/d of cinnamaldehyde and 0.3 g/d of eugenol (CIE) on rumen fermentation. Each period consisted of 15 d for adaptation and 6 d for sampling. On d 16, 17 and 18 of each period, DM and water intake were measured. On d 19, 20 and 21 ruminal content was sampled at 0, 3, 6, 9 and 12 h after feeding to determine ruminal pH and the concentration of volatile fatty acids (VFA), L-lactate, large peptides (LPep), small peptides plus AA (SPep+AA) and ammonia N. On d 20 and 21, samples of rumen fluid were also taken at 0 and 3 h after feeding to determine protozoa counts. On d 21, rumen fluid was used to determine in vitro DM and CP degradation of alfalfa hay, ryegrass hay, barley grain, wheat grain, corn grain and soybean meal (SBM) after 4 and 24 h incubation. Relative to CTR, treatments had no effect on ruminal pH, total VFA concentration and butyrate proportion. The CAP increased (P<0.05) DM and water intake, and SPep+AA N concentration, reduced (P<0.05) acetate proportion and LPep N concentration. The CIE reduced (P<0.05) water intake, acetate proportion, L-lactate, and ammonia N concentrations, and total protozoa counts, and increased (P<0.05) propionate proportion and SPep+AA N concentration. The ANI reduced (P<0.05) acetate to propionate ratio, and ammonia N concentrations, and total protozoa counts. In vitro, ANI, CAP, and CIE reduced (P<0.05) CP degradation of SBM at 4 h after incubation, and only ANI reduced CP degradation of SBM at 24 h after incubation. Results indicate that CIE, ANI and CAP may be useful as modiflers of rumen fermentation in beef production systems. [ABSTRACT FROM AUTHOR]

Forage grass production is an important component of profitable dairying along the Pacific Northwest coast. Neutral detergent fiber digestibility (NDFD) is increasingly being used in ration formulation and forage benchmarking. However, data on differences in NDFD between and within cool-season grass species is limited. Therefore, the objective of this study was to determine if NDFD differs between and within species. In experiment 1, 15 cool-season grass varieties were replicated 3 times each in 6 m2 randomized field plots. Included were 5 varieties each of perennial ryegrass (Lolium perenne), orchardgrass (Dactylis glomerata), and tall fescue (Lolium arundinaceum). In experiment 2, three diploid and three tetraploid cool-season ryegrass varieties (Lolium perenne) were replicated 3 times each in 6 m2 randomized field plots. Plots were mechanically harvested six times at approximately 28 d intervals beginning in March. Forty eight-hour in vitro neutral detergent fiber (NDF) digestibility was determined using 0.3 g of sample in F57 bags in a DaisyII Incubator (Ankom Technology, Fairport, NY). In experiment 1, yield (2124±79 kg DM/ha/cutting) was similar across species. Neutral detergent fiber was less for ryegrass compared to orchardgrass (47.1 vs 48.5±0.4%; P < 0.01), but similar to both of these grasses was tall fescue (48.0%). Neutral detergent fiber digestibility was greater for ryegrass compared to orchardgrass and tall fescue (80.4 vs 77.5±0.6% of NDF; P < 0.01). Digestible NDF did not differ and was 37.4±0.3% of DM or 799±32 kg/ha/cutting. Neutral detergent fiber increased (linear; P < 0.01) and NDFD decreased (quadratic, cubic; P < 0.05) as the growing season progressed. In experiment 2, yield (2220±110 kg DM/ha/cutting), NDF (47.2±0.5%), NDFD (80.7±0.5%), and digestible NDF (38±0.4% of DM and 851±47 kg DM/ha/cutting) were similar for diploid and tetraploid ryegrasses. These results indicate species, when managed intensively, has little effect on yield and digestibility. [ABSTRACT FROM AUTHOR]

Discusses the abstract of the study 'The effect of early calf weaning followed by rye-grass (Lolium multiform) grazing on performance of fall-born cavles in Florida,' presented at the American Society of Animal Science's Southern Section conference on January 31-February 4, 2003, in Mobile, Alabama.