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Increased colostrum lactose concentration is also associated with greater colostrum yield and reduced protein and Brix% in dairy cattle ([83]), supporting the concept that colostrum yield may dilute component concentrations. Imposing mid to late-gestation nutrient restriction reduced first-milking colostrum yield (within 1 h postcalving) in beef cattle ([56]; [72]) without altering colostrum IgG concentration ([56]; [72]) but compromised total IgG yield ([72]). Colostrum IgG yield is often not reported in dairy and beef cattle, although one study noted that there was no difference in colostrum IgG output between treatments, despite colostrum IgG concentration being decreased ([84]). By contrast to cattle, colostrum yield in sheep appears more sensitive to protein supplementation during late gestation, with most studies indicating that increased protein intake (at times, in conjunction with greater RUP intake) increases colostrum yield ([38]; [3]). Keywords: cattle; colostrum; immunoglobulin G; prepartum; nutrition; sheep EN cattle colostrum immunoglobulin G prepartum nutrition sheep 24 36 13 06/20/23 20230601 NES 230601 Implications Many cattle and sheep do not produce enough colostrum for their offspring. [Extracted from the article]

During transient periods of feed restriction (FR), ruminal ammonia-N (NH3-N) concentrations and fluid volume may parallel the reduction in feed and water intake. However, changes in ruminal digesta characteristics and NH3-N during FR have not been characterized. Thus, the objective was to determine how FR duration impacts ruminal digesta weight and the liquid and solid fractions, and ruminal NH3-N concentration. Lambs (n = 9 wethers and 12 rams, stratified by BW and castration status) were fed ad libitum (AL, n = 7) or subjected to 5-d (FR5, n = 7) or 10-d of FR (FR10, n = 7) at 30% of AL intake. Lambs were killed 4 h post-feeding to excise the gastrointestinal tract and ruminal digesta was weighed. Sub-samples of digesta were collected for separation into solid and liquid fractions using a winepress, used for DM determination, and another was strained and preserved with sulfuric acid to analyze ruminal NH3-N concentration. Data were analyzed with PROC GLIMMIX (SAS 9.4) with the fixed effect of treatment and random effects of lamb specified to the R-sided matrix. Linear regression (PROC REG) was used to evaluate the relationship between ruminal NH3-N concentration and quantity relative to ruminal fluid weight and PROC CORR was used to generate Pearson correlation coefficients. The ruminal digesta weight did not differ (P = 0.97) among treatments but AL ruminal digesta was drier (P < 0.01) than FR5 and FR10 digesta (40.2% decrease in DM% relative to AL). As such, FR5 and FR10 had 0.7 ± 0.16 kg less (P = 0.01) ruminal solids than AL while they tended to have more (P = 0.09) ruminal fluid. Ruminal NH3-N concentration was greater (P < 0.01) for FR5 and FR10 compared with AL (2.4 and 2.0 vs. 0.4 ± 0.52 mg/dL, respectively). The quantity of ruminal NH3-N (mg) followed the same pattern with FR5 and FR10 having, on average, 51.5 ± 18.39 mg NH3-N more (P < 0.01) in their ruminal fluid than AL. The quantity of ruminal NH3-N was strongly correlated (ρ = 0.87, P < 0.01) to the total ruminal fluid such that 75% of the variance was explained by the relationship. The strength of the correlation (ρ = 0.81, R² = 0.66, P < 0.01) between ruminal NH3-N concentration and total ruminal fluid was slightly lesser, but the two parameters were still strongly associated. From these data, we surmise that FR is associated with a reduction in ruminal DM content and may increase ruminal liquid that corresponds to increased ruminal NH3-N, independent of the duration of exposure. [ABSTRACT FROM AUTHOR]

The objective of this study was to determine the effect of 5 and 10 d low feed intake (LF) on the ruminant gastrointestinal tract (GIT). Twelve rams and nine wethers were used in a randomized complete block design where they were blocked by castration status and BW. After 5 d of ad libitum feeding, lambs were either exposed to 0 (CON; 100% DMI; n = 7), 5 (LF5; 30% DMI; n = 7), or 10 d (LF10; 30% DMI; n = 7) of LF. At the end of the study, lambs were euthanized, the GIT was removed to determine the digesta and tissue weights by region and the weights of the liver, spleen, and kidneys were recorded. There were no castration × treatment interactions (P = 0.32). Initial (P = 0.97) and final (P = 0.19) BW did not differ by treatment. The weight of the reticulo-ruminal tissue tended to be less (P = 0.06) for LF10 than CON, with LF5 being intermediate but not different. Ruminal digesta weight was not affected (P = 0.98). Omasal tissue weight did not differ among treatments (P = 0.24), but digesta weight tended (P = 0.07) to be greater for CON compared with LF10 and LF5. Abomasal tissue weight was reduced for LF10 (P = 0.04), with LF5 being intermediate but not different. Abomasal digesta weight was less for LF5 and LF10 than CON (P = 0.04). The weight of the duodenum tended (P = 0.08) to be greater for CON than LF10 and LF5, but digesta weight was not affected (P = 0.16). For the jejunum, tissue and digesta weight tended (P = 0.07) to be greater for CON than LF10, with LF5 being intermediate. The weight of the ileum tended to be the greatest for CON, intermediate for LF5, and the least for LF10 (P = 0.10), but digesta weight was not affected (P = 0.81). Cecal tissue weight was not affected by treatment (P = 0.89); whereas digesta weight was the greatest (P = 0.03) for LF10, the least for CON, and intermediate but not different for LF5. In contrast, colonic tissue weight was less for LF10 relative to LF5 and CON (P = 0.01) and digesta weight tended (P = 0.05) to be greater for CON than LF5 and LF10. Liver weight was reduced (P < 0.01) for both LF5 and LF10 relative to CON, but kidney and spleen weights were not affected (P = 0.33). This study indicates that exposing ruminants to LF rapidly reduces the weights for regions of the GIT and liver. These changes likely implicate a reduced absorptive capacity of the GIT and a lesser metabolic capacity of the liver. [ABSTRACT FROM AUTHOR]

The objective of the study was to determine the effect of oversupplying MP during late gestation on maternal BW, ruminal fermentation, nitrogen balance, and skeletal muscle catabolism. Crossbred Hereford heifers (n = 24) were assigned to a control treatment designed to meet MP requirements (CON) or a treatment providing 133% of the MP requirement (HMP). Heifers were individually fed their treatment from day −55 ± 3 relative to parturition and DMI was summarized by week. BW was measured on day −55 ± 3, −41 ± 3, −27 ± 3, and −8 ± 3. Ruminal digesta samples were collected on day −34 ± 5 and −15 ± 4 for short-chain fatty acid and ammonia-N (NH 3 -N) concentration. Plasma was collected the day prior to ruminal digesta samples and analyzed for plasma urea-N. Nitrogen balance was measured over a 6-d period starting on day −34 ± 4 and −15 ± 4. Following completion of the N balance periods, muscle biopsies were collected from the longissimus dorsi and analyzed for abundance of proteins relating to skeletal muscle catabolism. Data were analyzed as a randomized complete block (date of parturition) design with repeated measures using the MIXED procedure of SAS. Heifers fed HMP increased conceptus-corrected BW by a greater magnitude than CON at day −8 relative to −55 and −41 (treatment × day, P < 0.01). DMI increased (P < 0.01) by 18% on week −2 compared to −8, but then decreased (P < 0.01) by 8.0% for week −1. N-intake, apparent N digestion, N excretion, and N retention (g/d) were all greater (P < 0.01) for HMP heifers than CON but did not differ when expressed as a proportion of N intake. Ruminal NH3-N decreased (treatment × day, P < 0.01) as parturition approached for HMP (10.1 to 8.6 mg/dL); whereas, NH3-N was not affected for CON (1.0 to 1.3 mg/dL). Consequently, plasma urea-N was greater (P < 0.01) for HMP heifers (15.0 vs. 7.5 mg/dL). Heifers fed HMP had improved (P < 0.01) DM, OM, and NDF digestibility relative to CON heifers. The abundance of calpastatin was greater (P = 0.03) and calpain tended to be greater (P = 0.085) for CON cows compared to HMP. Feeding greater quantities of MP during late gestation may improve ruminal fermentation, N balance, and improve BW gain prepartum. [ABSTRACT FROM AUTHOR]

The objective of the study was to determine whether oversupplying MP prepartum affects postpartum cow BW, colostrum composition, milk production and composition, protein catabolism in the dam, and calf growth. Crossbred Hereford heifers were individually fed a control treatment designed to meet MP requirements (CON ; n = 10) or 133% of the MP requirement (HMP ; n = 11) from day −55 ± 4 until parturition. All cows were provided a common postpartum diet. Cow BW was measured on days 7 ± 1, 14 ± 2, 28 ± 3, 57 ± 4, 82 ± 5, and 111 ± 3 relative to parturition. DMI and ruminal pH were measured daily and summarized by week until day 33. Milk yield was estimated based on a 12-h two-quarter milk yield on days 7 ± 1, 12 ± 1, 28 ± 3, 33 ± 3, 70 ± 3, and 112 ± 3. Urine samples were collected from cows over a 6-d period starting on days 7 ± 1 and 28 ± 3 and the composited samples were analyzed for 3-methylhistidine (3-MH) and creatinine. Muscle samples were collected from cows on day 13 ± 1 while calf muscle samples were collected on days 2 and 111 ± 3 of age. Muscle samples from cows were analyzed for markers of protein catabolism, and calf muscle samples were analyzed for genes regulating cell growth and differentiation. Data were analyzed as a randomized complete block design using the MIXED procedure of SAS accounting for repeated measures when necessary. Postpartum BW did not differ (P ≥ 0.30) by treatment, day, or the interaction of treatment and day (T × D), but rump fat decreased (P = 0.011) as lactation progressed. DMI decreased during weeks 2 and 3 compared to 1 and 4, whereas ruminal pH was less during weeks 2, 3, and 4 relative to week 1. Colostrum fat concentration was less (P = 0.003) for HMP than CON; but, milk production was not affected by treatment. Milk yield was greatest from days 7 to 33 and decreased thereafter (P < 0.01). Urinary 3-MH and the 3-MH:creatinine ratio did not differ by treatment, day, or the T × D (P ≥ 0.22) interaction, nor was there a difference (P ≥ 0.13) in the abundance of catabolic proteins. Calf growth was not affected by treatment, but HMP calves had greater expression (T × D, P = 0.05) of PPARG while PKM expression increased for CON calves (T × D, P = 0.04) at day 111 compared to their expression at day 2. Overfeeding MP during late gestation does not improve postpartum indicators of N balance or maternal muscle turnover but may alter colostrum composition and calf gene expression at weaning. [ABSTRACT FROM AUTHOR]

Insulin concentrations are variable in bovine colostrum (5 to 263 μg insulin/L) and its effects on gastrointestinal function in neonatal calves are unknown. The objective of this study was to determine if varying concentrations of insulin in colostrum would influence intestinal carbohydrases in neonatal Holstein bulls. Calves (n = 26; 49.11 kg, SD = 3.24) were removed from their dams after calving. They were fed 3 meals of colostrum (7% BW or 3.10 ± 0.02 L) at 2, 14 and 26 hours after birth containing one of 3 insulin concentrations: basal (16.8 μg/L; n = 8), or supplemental colostrum containing either a 5× (83.4 μg/L; n = 10) or 10× (167.5 μg/L; n = 8) increase in colostrum insulin respective to basal concentrations. At 30 hours, the animals were killed, and the gastrointestinal tract was removed for mucosal scrapings of the duodenum, proximal jejunum, and ileum. Intestinal mucosal scrapings were assayed for the following brush border carbohydrases: maltase, isomaltase, lactase and glucoamylase. Data were analyzed using the MIXED procedure of SAS with treatment and dam parity modeled as fixed effects. There was no treatment effect (P > 0.05) on intestinal maltase, isomaltase and glucoamylase concentrations. However, there was a linear increase (P < 0.05) in jejunal lactase activity (Unit/g of jejunum and U/g of protein) with increasing amount of insulin inclusion. These data indicate that insulin supplementation has minimal effects on activities of brush border starch degrading enzymes, but increases lactase activity in the proximal jejunum of neonatal calves. [ABSTRACT FROM AUTHOR]

We evaluated how metabolizable energy (ME) intake influences antepartum insulin sensitivity in beef cattle. Angus-Simmental cattle (primiparous: n = 17; multiparous: n = 21) were randomly assigned to treatments supplying 80 (LowME, n = 19) or 120% (HighME, n = 19) of predicted ME requirements for 53 d prepartum. At 7 d antepartum, intravenous glucose tolerance tests (IVGTT) were imposed by infusing 1.36 g glucose/kg BW0.75 and sampling from -3 to 90 min to measure plasma glucose and insulin and serum non-esterified fatty acids (NEFA) concentrations. Data were analyzed using PROC GLIMMIX with the fixed effects of treatment, parity, time (repeated), and treatment×time and considering cow(treatment) as random. Baseline glucose concentration increased (P = 0.03) and baseline insulin concentration tended to increase (P = 0.06) for HighME relative to LowME cattle irrespective (P = 0.33) of parity, whereas baseline NEFA concentration was elevated (P < 0.01) for LowME vs. HighME. Plasma glucose-insulin concentrations during the IVGTT did not differ (P = 0.25) by treatment, treatment×time, or parity. However, serum NEFA was elevated (P < 0.01) throughout the IVGTT for LowME vs. HighME cattle and tended to be affected (P = 0.09) by the treatment×time interaction as NEFA concentrations became similar at 90 min due to HighME cattle having a shallower (treatment×time: P < 0.01) decremental NEFA response than LowME cattle. Low ME cattle cleared NEFA more quickly (75% increase; P < 0.01) than HighME. The glucose positive incremental area-under-the-curve throughout the IVGTT tended to be lesser (P = 0.06) for heifers than cows but heifers had a blunted (P = 0.05) glucose-stimulated reduction in NEFA and NEFA clearance rate compared to cows. These data demonstrate that ME provision may alter adipose insulin responsiveness in antepartum beef cattle and that heifers respond to excess glucose and NEFA differently than cows. [ABSTRACT FROM AUTHOR]

This study evaluated how late gestation metabolizable energy (ME) intake affects performance and metabolism in beef cattle. Primiparous (PP; n = 45) and multiparous (MP; n = 107) Angus-Simmental cows were blocked by calving date and randomly assigned to treatments providing 80 (LME; n = 52), 100 (CME; n = 51), or 120% (HME; n = 49) of ME requirements for 53 d prior to calving. Postpartum, cows were fed the same diet. Rib and rump fat depths were measured by ultrasonography on d -54, -40, -26, -13, 13, 27, and 55 relative to calving. Plasma and serum were collected on d -53, -39, -25, -10, -3, 7, 13, 27, and 55 relative to calving. Serum glucose, beta-hydroxybutyrate, nonesterified fatty acids (NEFA), and urea, and plasma insulin were measured. Data were analyzed using PROC GLIMMIX with the fixed effects of treatment, parity, and treatment×parity, and random effects of block and cow (block), accounting for repeated measures. Absolute loss of rib and rump fat prepartum was lesser (P = 0.03) for HME. Primiparous heifers lost more (P < 0.01) rib fat prepartum. Prepartum serum urea and NEFA were elevated (P < 0.01) for LME, whereas glucose was elevated (P < 0.01) for HME compared to LME. Multiparous cows had greater (P = 0.02) serum NEFA and plasma insulin prepartum, whereas PP heifers had elevated (P < 0.01) glucose. Treatment did not affect (P = 0.56) the absolute loss of rib nor rump fat postpartum. Serum urea was greater (P < 0.01) in LME than HME postpartum. Multiparous cow serum urea and beta-hydroxybutyrate postpartum was elevated (P = 0.01) postpartum, whereas PP cows had elevated (P < 0.01) plasma insulin. Supplementing excess ME during late gestation reduced mobilization of body reserves before calving but prepartum effects did not continue postpartum. [ABSTRACT FROM AUTHOR]

The objective was to determine how late gestation metabolizable energy (ME) intake impacts beef cow colostrogenesis. Angus-Simmental primiparous (n = 47) and multiparous (n = 109) cattle were blocked by expected calving date and randomly assigned to receive diets that supplied 80% (LME; n = 53), 100% (CME; n = 52), or 120% (HME; n = 51) of the ME requirement. Treatments were balanced by initial BW and fed for 53 d prior to calving. Cow body weight was recorded d -53, -39, -25, -10, and -3 relative to calving and retrospectively conceptus-corrected. Calves were weighed and measured prior to suckling. Colostrum was hand-stripped from all cows for compositional analysis and a subset (n = 16/treatment) was fully milked using a milking machine. Data were analyzed (PROC GLIMMIX) as a randomized block design, including the fixed effects of treatment, parity, and treatment×parity and the random effects of block and cow(block). Day and its interactions were included for repeated measurements. Treatment did not affect (P ≥ 0.73) cow BW or conceptus-corrected BW. Calf chest circumference was lesser (treatment×parity: P = 0.023) for primiparous vs. multiparous calves if their dams consumed LME or CME, but not if their dams consumed HME. Feeding HME rather than LME increased (P = 0.006) colostrum yield. The LME diet increased (P = 0.004) colostrum IgG concentration over HME; however, HME colostrum yielded more (P = 0.005) total IgG. Crude protein and urea-N were elevated (P < 0.001) in LME colostrum, whereas HME colostrum contained more (P = 0.026) lactose. Low ME colostrum fat was greater (P = 0.013) than CME and beta-hydroxybutyrate was increased (P < 0.001) in LME vs. CME and HME colostrum. These data provide insight regarding nutrient partitioning during late gestation and demonstrate that beef cow colostrogenesis is responsive to prepartum ME intake. [ABSTRACT FROM AUTHOR]