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Growth rates associated with different artificial rearing systems have been thoroughly examined in many species. However, the effect of different rearing systems on bone morphology has not been described. The objective of this study was to examine differences in the bone mass and the relationship of peripheral quantitative computed tomography (pQCT) measures of bone with muscle area of ewe-reared lambs and artificially reared lambs. Lambs were opportunistically collected from a concurrent trial examining changes in ewe mammary glands during lactation. Thirteen lambs were artificially reared while the remaining nine were left on their dam. Measures of stature were taken throughout the six-week trial period. At approximately six weeks of age, the lambs were euthanized and the tibia was collected and scanned using peripheral quantitative computed tomography. Artificially reared lambs had reduced live weight gain and an altered pattern of stature growth. There was no effect of treatment on bone morphology (p > 0.05), but ewe reared lambs had a greater cortical bone content to muscle area ratio than artificially reared lambs (0.06 vs. 0.15, respectively). Differences in growth between ewe reared lambs and artificially reared lambs emphasizes the importance of adequate preweaning nutrition for livestock production systems that routinely use artificial rearing systems.

Simple Summary Optimum lamb growth and cost-effective artificial lamb rearing are important to maximise farm profit. In addition to milk feeding, supplementation of a solid feed with balanced nutrients and an adequate level of fibre will aid rumen development, allowing for a smooth transition from a liquid to a solely solid diet. This study aimed to determine the effect of pellet fibre level, milk replacer composition and early milk weaning at 42 days of age, on the growth and body composition of lambs reared artificially to 57 days of age. Results demonstrate that lamb growth rate to 57 days of age was not affected by early weaning or pellet fibre level. Early milk weaning increased pellet intake and empty rumen weight. Early weaning resulted in leaner carcasses due to reduced fat deposition and lower total feed costs compared to lambs offered milk to 57 days of age. Overall, feeding lambs either low or high fibre pellets and weaning early (42 days of age) was shown to be beneficial, as growth was similar to unweaned lambs, but leaner carcasses and reduced feed costs were observed. Abstract This study was designed to investigate the influence of pellet fibre level, milk replacer composition and age at weaning on growth and body composition of lambs reared artificially. Romney ram lambs were randomly allocated to one of three rearing treatments; HFP57: commercial milk replacer to 57 days of age, and high fibre concentrate pellets; HFP42: commercial milk replacer with early weaning at 42 days of age, and high fibre concentrate pellets; LFP42: high protein milk replacer from 2–16 days of age followed by commercial milk replacer with early weaning at 42 days of age, and low fibre concentrate pellets. Lambs were slaughtered at 57 days of age. Overall average daily liveweight gain of lambs did not differ (p > 0.05) between treatments. Dressing out percentage, carcass weight, empty small intestine and omental fat were higher (p < 0.05) in HFP57 than in both HFP42 and LFP42 lambs. HFP42 and LFP42 lambs had heavier (p < 0.05) empty rumen weights. Whole body protein content was higher (p < 0.05) in HFP42 lambs compared to both HFP57 and LFP42 lambs. Fat content and daily fat deposition were greater (p < 0.05) in HFP57 lambs than HFP42 and LFP42 lambs. Weaning lambs at 42 days of age with provision of either low or high fibre concentrate pellets, resulted in similar growth rates, reduced whole body fat deposition and was a more cost-effective rearing regimen.

New Zealand hill country sheep and beef farms contain land of various slope classes. The steepest slopes have the lowest pasture productivity and livestock carrying capacity and are the most vulnerable to soil mass movements. A potential management option for these areas of a farm is the planting of native shrubs which are browsable and provide erosion control, biodiversity, and a source of carbon credits. A bioeconomic whole farm model was developed by adding a native shrub sub-model to an existing hill country sheep and beef enterprise model to assess the impacts on feed supply, flock dynamics, and farm economics of converting 10% (56.4 hectares) of the entire farm, focusing on the steep slope areas, to native shrubs over a 50-year period. Two native shrub planting rates of 10% and 20% per year of the allocated area were compared to the status quo of no (0%) native shrub plantings. Mean annual feed supply dropped by 6.6% and 7.1% causing a reduction in flock size by 10.9% and 11.6% for the 10% and 20% planting rates, respectively, relative to 0% native shrub over the 50 years. Native shrub expenses exceeded carbon income for both planting rates and, together with reduced income from sheep flock, resulted in lower mean annual discounted total sheep enterprise cash operating surplus for the 10% (New Zealand Dollar (NZD) 20,522) and 20% (NZD 19,532) planting scenarios compared to 0% native shrubs (NZD 22,270). All planting scenarios had positive Net Present Value (NPV) and was highest for the 0% native shrubs compared to planting rates. Break-even carbon price was higher than the modelled carbon price (NZD 32/ New Zealand Emission Unit (NZU)) for both planting rates. Combined, this data indicates planting native shrubs on 10% of the farm at the modelled planting rates and carbon price would result in a reduction in farm sheep enterprise income. It can be concluded from the study that a higher carbon price above the break-even can make native shrubs attractive in the farming system.

Twin sets of lambs were randomly allocated to one of six treatments: (1) lambs born and managed on ryegrass&ndash, clover-based pasture until conventional weaning approximately at 99 days of age (Grass&ndash, GrassCW), (2) lambs born on ryegrass&ndash, clover-based pasture and early weaned onto a herb&ndash, clover mix at ~45 days of age (Grass&ndash, HerbEW), (3) lambs born on ryegrass&ndash, clover-based pasture, transferred with their dam onto a herb&ndash, clover mix at ~45 days of age until conventional weaning (Grass&ndash, HerbCW), (4) lambs born on ryegrass&ndash, clover mix at ~15 days of age and early weaned onto a herb&ndash, HerbD15EW), (5) lambs born and managed on herb&ndash, clover mix until conventional weaning (Herb&ndash, (6) lambs born on herb&ndash, clover mix and weaned early onto a herb&ndash, clover mix at ~45 days of age (Herb&ndash, HerbEW). In both years, Herb&ndash, HerbCW lambs had greater (p &lt, 0.05) growth rates than lambs in other treatments. The liveweight gains and rumen papillae development of Herb&ndash, HerbEW, Grass&ndash, HerbD15EW and Grass&ndash, HerbEW lambs did not differ (p &gt, 0.05). The weight of the empty digestive tract components at either early weaning or conventional weaning did not differ (p &gt, 0.05) between treatments. Exposing early-weaned lambs to the herb mix for a prolonged period, prior to early weaning, does not improve their subsequent growth.

The foetal mammary gland is sensitive to maternal weight and nutrition during gestation, which could affect offspring milk production. It has previously been shown that ewes born to dams offered maintenance nutrition during pregnancy (day 21 to 140 of gestation) produced greater milk, lactose and CP yields in their first lactation when compared with ewes born to dams offered ad libitum nutrition. In addition, ewes born to heavier dams produced greater milk and lactose yields when compared with ewes born to lighter dams. The objective of this study was to analyse and compare the 5-year lactation performance of the previously mentioned ewes, born to heavy or light dams that were offered maintenance or ad libitum pregnancy nutrition. Ewes were milked once per week, for the first 6 weeks of their lactation, for 5 years. Using milk yield and composition data, accumulated yields were calculated over a 42-day period for each year for milk, milk fat, CP, true protein, casein and lactose using a Legendre orthogonal polynomial model. Over the 5-year period, ewes born to heavy dams produced greater average milk (P=0.04), lactose (P=0.01) and CP (P=0.04) yields than offspring born to light dams. In contrast, over the 5-year period dam nutrition during pregnancy did not affect average (P>0.05) offspring milk yields or composition, but did increase milk and lactose accumulated yield (P=0.03 and 0.01, respectively) in the first lactation. These results indicate that maternal gestational nutrition appears to only affect the first lactational performance of ewe offspring. Neither dam nutrition nor size affected grand-offspring live weight gain to, or live weight at weaning (P>0.05). Combined these data indicate that under the conditions of the present study, manipulating dam weight or nutrition in pregnancy can have some effects of offspring lactational performance, however, these effects are not large enough to alter grand-offspring growth to weaning. Therefore, such manipulations are not a viable management tool for farmers to influence lamb growth to weaning.

Plantain (Plantago lanceolata L.) contains bioactive compounds with antimicrobial activity that can potentially influence ruminal fermentation. This study aimed to identify the concentration of the bioactive compounds catalpol, aucubin, and acteoside in plantain cv. ‘Ceres Tonic’ through two consecutive growing seasons (2011–2012 and 2012–2013). Then the herbage with highest levels of bioactive compounds was used to evaluate their effect on rumen in vitro fermentation. Plantain cv. ‘Ceres Tonic’ had almost nil concentration of catalpol. Both aucubin and acteoside concentrations increased (P

The objective of this study was to investigate the gene expression of progesterone and estrogen receptor α (PR, ERα), insulin-like growth factor (IGF) 1, IGF-2, their receptor (IGFR1), IGF-binding proteins (BP) 1 to 6, insulin receptor, adiponectin receptors (AdipoR1/2), cyclooxygenase 2 (PTGS2), mucin 1 and to localize PR, ERα, IGF-1, IGFR1, PTGS2, and proliferating cellular nuclear antigen (PCNA) in the endometrium of pregnant (Day 19) Suffolk and Cheviot ewes carrying Suffolk and Cheviot embryos transferred within and reciprocally between breeds. Gene expression was determined by real-time quantitative polymerase chain reaction (RT-qPCR), and antigen determination was measured by immunohistochemistry in the luminal epithelium (LE), superficial and deep glands (SG, DG, respectively) and superficial and deep stroma. Gene expression of PR, IGF-1, IGFBP2, and IGFBP5 was higher in Suffolk than that in Cheviot ewes (P

Milk replacers adjusted for crude protein to metabolizable energy (CP:ME) ratio to match the lambs’ changing requirement during first few weeks post-birth have resulted in higher pre-weaning lamb growth rate compared to commercial milk replacers with a static CP:ME ratio. This study aimed to determine if milk replacer with an adjusted CP:ME ratio to meet the lambs changing CP:ME requirement over time improved lambs growth performance during both the pre-and post-weaning periods. Twenty-seven Romney twin-born ram lambs were assigned to one of two pre-weaning milk feeding treatments: i) a commercial milk replacer (CMR, n = 14; CP:ME 12.28 g/MJ); or ii) a regularly adjusted blend of commercial milk replacer and milk protein concentrate (MB, n = 13; CP:ME starting at 16.6 g/MJ and adjusted down to approximately 13 g/MJ). All lambs were fed at 2.1 times their maintenance energy requirement. The CP:ME ratio of the MB treatment was adjusted twice-weekly to match the changing CP:ME requirements. All the lambs had ad libitum access to pellets. Lambs were weaned at 22 kg live weight (LW), transferred to a ryegrass and white clover-based pasture and reared approximately to 46 kg LW. The LW during pre- and post-weaning was recorded twice weekly and fortnightly, respectively. In the pre-weaning period, total daily CP intake and daily CP intake from milk were greatest (P 0.05) between treatments. Lambs fed MB had greater total and milk CP:ME intake (P 0.05) between treatments. The ME intake per kilogram LW gain during the pre-weaning did not differ (P > 0.05) between treatments. The CP intake per kilogram LW gain during the pre-weaning was higher (P 0.05) between treatments. There was no correlation (P > 0.05) in overall ADG of lambs between pre-and post-weaning periods. The ADG during day one to ten at the start of experiment had a positive and significant effect on the overall post-weaning ADG (r = 0.570, P = 0.007) and ADG in first two weeks (r = 0.470, P = 0.032) of the post-weaning phase. Similar pre-and post-weaning growth rates were observed for lambs in both treatment groups, despite the pre-weaning adjustment of CP:ME to meet lambs requirements. The CMR feeding was cost effective as the pre-weaning feed cost per kilogram live weight gain was lower than that of milk blend feeding. As CMR lambs likely obtaining additional CP from pellet intake during pre-weaning, further research is warranted on the effect of CP:ME ratio of pellets, pellet intake and digestibility on growth performance of lambs reared artificially.

This study aimed to determine the effect of changing the dietary crude protein to metabolisable energy ratio (CP:ME) of milk replacer on growth and body composition of pre-weaned lambs. Thirty-two Romney twin-born ram lambs were selected with four lambs being slaughtered at 24 h post-partum to estimate initial body composition. The remaining twenty-eight lambs were assigned to one of three nutritional treatments. Treatments consisted of either (i) a commercial milk replacer (CMR, n = 10); (ii) a high protein milk replacer (HPM, n = 9) or (iii) a mix of normal milk replacer and milk protein concentrate (MB, n = 9). All lambs were fed at 2.1 times their maintenance requirement. The CP:ME ratio of MB was adjusted twice-weekly to match the lambs CP and ME requirements for growth and maintenance over time. All lambs were slaughtered at 22 kg live weight (LW). The LW and chemical composition of carcass and viscera plus blood were determined. The combined CP:ME ratio of milk and pellets was greater for the HPM lambs than MB lambs, which was greater (P 0.05). Average daily LW gain was higher (P 0.05) for either parameters. Fat content of the carcass and viscera plus blood was lowest (P 0.05) between CMR and MB. Lambs fed HPM had lower (P 0.05). In conclusion, adjusting the CP:ME ratio of milk replacer to match the lambs’ theoretical requirement improves growth performance of artificially reared lambs. Further studies are required to determine the optimal CP:ME ratio effect of milk replacer, its cost effectiveness and to examine post-weaning growth effects.

A high proportion of piglets fail to adapt to the changing composition of their diet at weaning, resulting in weight loss and increased susceptibility to pathogens. Polyamines are present in sow milk and promote neonatal maturation of the gut. We hypothesised that oral spermine and spermidine supplementation before weaning would increase piglet growth and promote gastrointestinal development at weaning. In Experiment One, one pair of liveweight (LW)-matched piglets per litter from first and third lactation sows received 2 ml of a 0 (Control) or 463 nmol/ml spermine solution at 14, 16, 18, 20 and 22 days of age (n=6 piglets/treatment per parity). Villus height and crypt depth in the duodenum and jejunum were measured at weaning (day 23 postpartum). In Experiment Two, piglets suckling 18 first and 18 third lactation sows were used. Within each litter, piglets received 2 ml of either water (Control), 463 nmol/ml spermine solution or 2013 nmol/ml spermidine solution at 14, 16, 18, 22 and 24 days of age (n=54 piglets/treatment per sow parity). Piglets were weighed individually at 14, 18, 24 (weaning) and 61 days of age. In Experiment One, oral spermine supplementation resulted in a 41% increase in villus height, a 21% decrease in crypt depth and 79% decrease in the villus height : crypt depth ratio compared with control piglets (P

This study examined the effects of maternal size at conception and nutrition during pregnancy on ovarian development in their offspring. Romney ewes were selected at mating for heavy (H) or light (L) live weights and body condition, and then allocated to either ad libitum (A) or pregnancy maintenance (M) nutrition from Days 21–140 of pregnancy, resulting in four treatment groups; HA, HM, LA and LM. Ewes were euthanised on Days 65 (P65), 100 (P100) and 140 (P140) of pregnancy to collect fetal ovarian tissue, which was processed for morphological evaluation and immunohistochemical study of AMH and GDF9 (P140 only). Fetuses from H-dams had more oocytes in the first meiotic prophase on P65 (P=0.05) than those from L-dams. On P100, LA-fetuses had more primordial and fewer primary follicles than did LM-fetuses (P

Embryo transfer of large sheep breed embryos (Suffolk) into small breed ewes (Cheviot) constrains birth size, but the maternal factors influencing fetal growth restriction are unknown. We hypothesized that reciprocal embryo transfer crosses between breeds of divergent size would affect pregnancy-related development of maternal insulin resistance in midgestation, thereby influencing fetal growth. Following superovulation, embryos were surgically collected 6 d postmating and transferred to recipients on the same day. Between- and within-breed transfers were performed. Between 60 and 70 d of pregnancy overnight-fasted ewes underwent hyperinsulinemic-euglycemic clamps for assessment of insulin sensitivity. Maternal insulin sensitivity did not vary with transferred lamb breed. Overall, Cheviot ewes tended to have higher fasting glucose (P = 0.068), fasting insulin (P = 0.052), and steady-state glucose (P = 0.065) concentrations than Suffolk ewes at the stage of pregnancy studied. As expected, transferred between-breed Suffolk lambs were born lighter (P = 0.014), and transferred between-breed Cheviot lambs tended to be heavier at birth (P = 0.056) than respective lambs transferred within breed. Midgestation insulin sensitivity does not appear to be a major factor constraining growth of large breed sheep fetus transferred into smaller breed or a factor in releasing constraint in growth of a small breed fetus within a larger breed ewe. However, as embryo size is already different between transferred groups by 19 d, factors other than maternal gestational insulin resistance may determine fetal growth in this embryo transfer paradigm.

It has previously been shown that both dam size and nutrition in pregnancy can affect individual performance traits of ewe offspring to three years of age. The objective of this study was to determine if dam size and nutrition during pregnancy affected lifetime productivity to six years of age in ewe offspring. In 2005, Romney ewes (G 0 ) were selected as heavy (H; n = 450, mean live weight = 60.8 ± 0.18 kg (s.e)) or light (L; n = 450; mean live weight = 42.5 ± 0.17 kg) based upon live weight at the time of mating, and then randomly allocated to receive pregnancy maintenance (M) or ad libitum (A) pasture feeding treatment from day 21 to 140 of pregnancy; resulting in four treatment groups (HA, HM, LA and LM). Live weight, body condition and reproductive performance data were recorded in the ewe offspring (HA n = 55, HM n = 58, LA n = 42 and LM n = 43) from 2007 to 2011 (580–2298 days of age). In addition live weights of their lambs (grand progeny) to weaning were recorded ( n = 1491 in total). Daughter live weights and body condition scores were inconsistently affected by dam size and nutrition over time and at most measurement points no differences ( P > 0.05) were found. At 2050 days of age A-daughters had higher proportion that ovulated than M-daughters ( P = 0.01) and A-daughters gave birth to more lambs than M-daughters ( P = 0.05), but there were no differences ( P > 0.05) found in relation to number or weight of lambs weaned. Daughters from H dams had a higher total number of antral follicles ( P = 0.018) and total number of follicles ( P = 0.05) at 2599 days of age, and greater proportion ( P = 0.016) of daughters that were present (survived) in the flock in 2011 compared to daughters from L dams. There were no interactions ( P > 0.05) between dam size and nutrition for any parameters of lifetime reproductive performance data collected. This study suggests that dam size and nutrition during pregnancy has a minimal impact on daughter lifetime performance. Therefore under the conditions of the present study farmers do not need to consider dam size and pregnancy nutrition when selecting progeny as replacement ewes.

The mammary gland is a complex tissue consisting of multiple cell types which, over the lifetime of an animal, go through repeated cycles of development associated with pregnancy, lactation and involution. The mammary gland is also known to be sensitive to maternal programming by environmental stimuli such as nutrition. The molecular basis of these adaptations is of significant interest, but requires robust methods to measure gene expression. Reverse-transcription quantitative PCR (RT-qPCR) is commonly used to measure gene expression, and is currently the method of choice for validating genome-wide expression studies. RT-qPCR requires the selection of reference genes that are stably expressed over physiological states and treatments. In this study we identify suitable reference genes to normalize RT-qPCR data for the ovine mammary gland in two physiological states; late pregnancy and lactation. Biopsies were collected from offspring of ewes that had been subjected to different nutritional paradigms during pregnancy to examine effects of maternal programming on the mammary gland of the offspring. We evaluated eight candidate reference genes and found that two reference genes ( PRPF3 and CUL1) are required for normalising RT-qPCR data from pooled RNA samples, but five reference genes are required for analyzing gene expression in individual animals ( SENP2, EIF6, MRPL39, ATP1A1, CUL1). Using these stable reference genes, we showed that TET1, a key regulator of DNA methylation, is responsive to maternal programming and physiological state. The identification of these novel reference genes will be of utility to future studies of gene expression in the ovine mammary gland.

Greater rates of genetic gain can be achieved by selecting animals born to younger parents. However, little is known about the lifetime performance of dual purpose ewes (Ovis aries) that are born to primiparous ewe lambs (8 to 9 months old at breeding). This experiment investigated the effect of being born from either a ewe lamb or mixed age dam as either a single or twin on the lifetime performance of ewe progeny. Lifetime performance was measured in terms of the life time live weights of the ewes, the weight and number of lambs born and weaned, the efficiency of production (kilograms of lamb weaned / predicted pasture intake (kgDM) of the ewes), and ewe survival. The study followed the lifetime production of 17 single and 41 twin female lambs born to mature ewes (M1 and M2, respectively), and 28 single and 29 twin lambs born to ewe lambs (L1 and L2, respectively). Over their lifetime L2 ewes were lighter (P

Studies using sheep models indicate that the fetal mammary gland is sensitive to maternal nutrition during gestation; however, results have been inconsistent and do not identify critical feeding periods. This study aimed to clarify previous findings by partitioning the period of maternal nutritional manipulation into 2 stages: early and mid-to-late pregnancy. Sixty-six twin-born, twin-bearing ewes, born to dams that were fed either submaintenance, maintenance, or ad libitum during early pregnancy (d 21 to 50 of pregnancy; SmP21-50, MP21-50, or AdP21-50, respectively) and then either maintenance or ad libitum during mid-to-late pregnancy (d 50 to 140 of pregnancy; MP50-140 or AdP50-140, respectively) were milked once a week, starting from d 7 ± 1 postpartum, for 7 subsequent weeks to enable estimation of daily milk yield and composition. Their lambs were weighed weekly. Ewes born to dams fed MP21-50 tended to have greater accumulated milk (P = 0.10), fat (P = 0.07), and NE (P = 0.06) yields over 50 d compared with ewes born to dams fed SmP21-50 and AdP21-50. In contrast, ewes born to dams fed AdP50-140 tended to have greater accumulated milk (P = 0.10) and lactose (P = 0.09) yields compared with ewes born to dams fed MP50-140. Grandoffspring birth weights were unaffected by granddam nutrition during pregnancy. Ewes born to dams fed AdP21-50 weaned lighter lambs (P = 0.05) than ewes born to dams fed AmP21-50 and tended to wean lighter lambs (P = 0.07) than ewes born to dams fed MP21-50 whereas there were no differences between the weaning weights of lambs (P = 0.43) from ewes born to dams fed AdP50-140 and MP50-140. Maintenance nutrition of dams during early pregnancy appears to be associated with an improved lactation performance of ewe offspring. Higher levels of nutrition during mid-to-late pregnancy also appears to improve the first-lactation performance of ewe offspring. Interestingly, although grandoffspring birth weights were unaffected, weaning weight appears to be influenced by granddam early pregnancy nutrition in a manner discordant with the lactational performance of their dam. Results from this study indicate that dam nutrition during early pregnancy can influence the lactational performance of ewe offspring and the BW at weaning of their grandoffspring, which may ultimately affect farmer profits. This highlights the importance of nutritional management of breeding ewes during this period.

Excessive mobilization of body reserves during lactation delays the return to reproductive function in weaned primiparous sows. This study tested the hypothesis that supplementing the lactation diets of first-parity sows with ractopamine hydrochloride would reduce maternal weight loss and improve subsequent reproductive performance. Gestating gilts were allocated to one of two treatment groups (n=30 sows/treatment), with one group fed a standard lactation diet (2.5g/Mcal LYS: DE) throughout lactation (CTRL), whereas the treatment group received the standard lactation diet supplemented with 10mg/kg ractopamine hydrochloride (RAC) from d 1 to 13 of lactation and 20mg/kg RAC from d 14 of lactation until artificial insemination (AI). Weaning occurred on d 21 of lactation, with AI occurring at the first post-weaning estrus. Compared to CTRL, RAC supplementation decreased (P

Yellowtail kingfish ( Seriola lalandi ) are farmed in sea cages in South Australian waters and exposed to seasonal variations in water temperature. The temperature variations, ranging from 10 to 24 °C, influence feed intake and on-farm feeding practices. Sub-adult yellowtail kingfish are fed twice daily in summer while feeding in winter may be reduced to once every second day. Lower winter water temperatures increase gut transit times which may lead to a condition known as winter syndrome. This syndrome causes an enteritis response in yellowtail kingfish and reduces farm productivity. The impact of water temperature on gut transit time, nutrient digestibility and protease and lipase enzyme activities in yellowtail kingfish (2.12 ±0.03 and 2.77 ± 0.03 kg live weight in summer and winter respectively) was investigated at summer and winter water temperatures; 20.8 ± 0.4 °C and 12.6 ± 0.1 °C respectively, using observations made on dissected fish and detection of the passage of dietary markers. Water temperature had a significant effect on gut transit time, with visual observations demonstrating that at summer water temperatures it takes 12–16 h for all digesta to be voided from the fish compared to 36–48 h at winter temperatures. Temperature did not have a significant effect on the dietary nutrient apparent digestibility coefficients (ADC, %) although there was a numerical tendency for nutrient ADC to be higher in the posterior intestine at summer water temperatures: 46% vs. 35% for dry matter; 70% vs. 67% for protein; 66% vs. 58% for fat; and 70% vs. 63% for energy. Nutrient digestibility did not differ significantly between the anterior and posterior intestinal sections; however, the ADC values were consistently higher in posterior intestine. Protease activity was significantly higher in the posterior intestine and there was also a numerical, but not significant, increase in protease and lipase activities in the anterior section of the intestine during winter. Lipase activity was significantly higher in the anterior intestine during summer, when compared to the posterior section, and numerically higher in this section during winter. In winter it was found that a greater proportion of nutrient digestion occurred in the stomach, pyloric caeca and anterior intestine when compared to summer. This was thought to be due to the slower gut motility and higher enzyme activities observed during winter. Even though gut transit time was slower in winter, the lower water temperature also resulted in nutrient digestibility that was numerically lower.

There is general acceptance that mixing sows during the first 3 weeks of gestation is detrimental to embryo development and survival. However, there is a paucity of data describing the influence of group housing and remixing during the first 14 days of gestation on pregnancy outcomes. Using 96 purebred maternal (Large White)/terminal (Duroc) line gilts, the current study determined the effects of regrouping, and the timing of regrouping, during the pre-implantation period on embryo mortality. The study was conducted in 2 blocks, with 12 gilts allocated to each of 4 treatments in each block. At 175 days of age, the combination of PG600 and 20 min of daily physical boar contact was used to stimulate puberty, with boar contact resuming 12 days after first detection of oestrus and gilts receiving two artificial inseminations (AIs), 24 h apart, at their second oestrus. After their first AI gilts were allocated to one of four treatment groups (n=12 gilts/treatment). Gilts in one treatment group were housed individually in stalls (STALL). The remaining gilts continued to be housed in their pre-AI groups and were either not remixed (NOMIX), or remixed to form new groups on day 3/4 (RMIXD3/4) or day 8/9 (RMIXD8/9) of gestation (day 0=day of first detection of second oestrus and first insemination). Group-housed gilts were housed in groups of 6, with a space allowance of 2.4 m2/gilt. All gilts were fed once a day (2.2 kg/gilt). Reproductive tracts were collected on day 26.6+/-0.13 of gestation, and the number of corpora lutea (CL) and viable embryos counted. Pregnancy rate was similar across all treatments, averaging 94.5% across the four treatment groups. The number of embryos present on day 26 of gestation was unaffected by housing treatments (P0.05); gilts in the STALL, NOMIX, RMIXD3/4 and RMIXD8/9 groups possessed 13.2+/-0.67, 12.9+/-0.66, 14.1+/-0.46 and 13.8+/-0.57 embryos, respectively. Similarly, embryo survival rates were 0.91+/-0.04, 0.85+/-0.04, 0.91+/-0.02 and 0.87+/-0.05 for the STALL, NOMIX, RMIXD3.4 and RMIXD8/9 groups, respectively (P0.05). In conclusion, the current data indicate that individually housing gilts immediately after their first AI does not improve embryo survival. There also appear to be no adverse effects on embryo development or survival when group-housed, mated gilts are remixed during the first 10 days of gestation.

Progesterone (P4) administration in early pregnancy enhances embryo growth in sheep but is associated with decreased embryo survival. This study examined the effects of exogenous P4 administered during specific time periods between pregnancy Day 0 and Day 6 to determine the critical time point for advancement of embryo growth without pregnancy loss and to examine Day 6 and Day 19 endometrial gene expression. Suffolk (S) embryos were transferred into Cheviot (C) ewes that received exogenous P4 (CP4) on Days 0–3 (CP40–3), Days 0–6 (CP40–6), Days 2–4 (CP42–4) or Days 3–6 (CP43–6). Additionally, S embryos were transferred to C and S ewes that did not receive P4 (CnP4 and SnP4). Day 19 embryos from CP4 ewes were longer (P

Progesterone (P4), acting via its receptor, regulates uterine function and histotroph production, which are crucial to embryo growth. This study aimed to examine exogenous P4 effects on embryo size and differential endometrial gene expression at Day 19 of gestation using a ‘dam size’ sheep model of maternal constraint. Purebred Suffolk (S, genotypically large) embryos were transferred into recipient groups of Cheviot (C, genotypically small) or Suffolk ewes that had, or had not, been pre-treated with P4 from Days 0 to 6 of pregnancy. At Day 19 S embryos were collected from four experimental groups: P4 pretreated S ewes (SP4; n = 5), untreated S ewes (SnP4; n = 15), P4 pretreated C ewes (CP4; n = 7) and untreated C ewes (CnP4; n = 21). Day-19 embryos from CP4 ewes were larger (P 0.05) to embryos from SnP4 and SP4 ewes. Expression of mucin 1 (MUC1) and prostaglandin-endoperoxide synthase 2 (PTGS2) was upregulated in uterine horns ipsilateral to the corpus luteum from CP4 ewes. Prostaglandin receptor (PGR), MUC1 and PTGS2 expression was upregulated, whilst cathepsin L (CTSL) and radical S-adenosyl methionine domain-containing 2 (RSAD2) expression was downregulated in the ipsilateral horn of SP4 ewes. This suggests that pretreating ewes with exogenous P4 may alleviate early pregnancy maternal constraint via mechanisms that alter uterine function. However, further research is required to investigate the timing of P4 administration and its impact on conception rates.

Background The mammary gland is a dynamic organ that undergoes dramatic physiological adaptations during the transition from late pregnancy to lactation. Investigation of the molecular basis of mammary development and function will provide fundamental insights into tissue remodelling as well as a better understanding of milk production and mammary disease. This is important to livestock production systems and human health. Here we use RNA-seq to identify differences in gene expression in the ovine mammary gland between late pregnancy and lactation. Results Between late pregnancy (135 days of gestation ± 2.4 SD) and lactation (15 days post partum ± 1.27 SD) 13 % of genes in the sheep genome were differentially expressed in the ovine mammary gland. In late pregnancy, cell proliferation, beta-oxidation of fatty acids and translation were identified as key biological processes. During lactation, high levels of milk fat synthesis were mirrored by enrichment of genes associated with fatty acid biosynthesis, transport and lipogenesis. Protein processing in the endoplasmic reticulum was enriched during lactation, likely in support of active milk protein synthesis. Hormone and growth factor signalling and activation of signal transduction pathways, including the JAK-STAT and PPAR pathways, were also differently regulated, indicating key roles for these pathways in functional development of the ovine mammary gland. Changes in the expression of epigenetic regulators, particularly chromatin remodellers, indicate a possible role in coordinating the large-scale transcriptional changes that appear to be required to switch mammary processes from growth and development during late pregnancy to synthesis and secretion of milk during lactation. Conclusions Coordinated transcriptional regulation of large numbers of genes is required to switch between mammary tissue establishment during late pregnancy, and activation and maintenance of milk production during lactation. Our findings indicate the remarkable plasticity of the mammary gland, and the coordinated regulation of multiple genes and pathways to begin milk production. Genes and pathways identified by the present study may be important for managing milk production and mammary development, and may inform studies of diseases affecting the mammary gland. Electronic supplementary material The online version of this article (doi:10.1186/s12864-015-1947-9) contains supplementary material, which is available to authorized users.

Small mixed farming systems in developing economies often rely on compensatory growth to recover livestock weight lost during seasonal feed shortages; however, deficit feed management may continue to affect the capacity of livestock to efficiently use feeds even after adequate feeding has resumed. Accordingly, we compared the difference in liveweight gain and feed utilisation over time in Tan weaner sheep in western China, during a period of ad libitum compensatory feeding after alternative feed deficit scenarios. During the feed deficit period, sheep were offered, at 80% maintenance requirements, corn straw, corn grain and lucerne hay in a respective ratio of either 80 : 20 : 0 (S1 ration: metabolisable energy = 7 MJ/kg DM, crude protein = 40 g/kg DM) or 55 : 20 : 25 (S2 ration: metabolisable energy = 8 MJ/kg DM, crude protein = 65 g/kg DM) for 20 days. All sheep were then offered an ad libitum supply of the S2 ration for a further 20 days, during which DM digestibility (DMD), energy intake and liveweight was measured and compared at 5-day intervals. Results indicated that sheep previously fed the S1 ration were not able to digest as much of the ad libitum S2 ration as those previously fed the S2 ration, experiencing significantly lower DMD, energy intake and average daily weight gain. The difference in the effect of the two restrictive feeding treatments on the digestibility of the ad libitum S2 ration gradually decreased over time, indicative of a recovery adaptation during ad libitum feeding period. The rate of DMD recovery post-realimentation was greater in the S1 sheep, likely due to their significantly lower DMD values immediately following underfeeding. We concluded that the comparatively higher nutritive value of the S2 ration sustained rumen digestive function throughout the restrictive feeding period, permitting sheep to commence re-feeding under conditions that are more favourable. Additionally, it is evident that reliance on livestock winter rations typical in western China, as expressed by the S1 ration, degraded ruminant digestive conditions to such an extent that feed was used with reduced efficiency even after being supplied in adequate quantities.

Within gilt pools, incidences of delayed puberty attainment, failure to exhibit regular oestrous cycles and low first litter size are often high. Boar exposure is an effective method of accelerating puberty; however, the timing of gilt response can vary greatly. Although, PG600 (400 IU of PMSG and 200 IU of hCG; Intervet) can induce a rapid and synchronous ovulatory response, thus providing an alternative to boar contact, the quality of the response is often variable. This study compared the effect of PG600, either alone (NBC) or in conjunction with boar exposure (BC), on puberty attainment and maintenance of oestrous cyclicity. The effects of first mating these gilts at the hormonally induced (pubertal) or second oestrus on ovulation rate and early embryo survival were also studied. Eighty Large White cross terminal (Duroc) line gilts were used in this study. The study was conducted in two blocks, with 10 gilts allocated to each of the four treatments in each block. Gilts were artificially inseminated at the allocated oestrus, with the reproductive tracts collected at 26.5+/-0.29 days after first mating (mean+/-S.E.M.), and the number of corpora lutea and viable embryos recorded. Mean days-to-puberty was significantly reduced (P

Socioeconomic and agro-ecological circumstances often compel smallholder livestock farmers in the developing world to maintain livestock over winter, and this can incur production penalties due to insufficient feed quality and availability. Recent policy efforts in western China have attempted to address this issue through the promotion of lucerne production to support growing livestock numbers with its high nitrogen content, however lucerne is underutilised by farmers and rarely maintained beyond harvest. The potential benefits to production of storing enough lucerne to meet the minimum nitrogen requirements of rumen function during the winter deficit were explored in an experiment in Qingyang Prefecture, Gansu Province, P.R. China. Tan weaner sheep (mean weight 15.4 kg) were fed corn straw, corn grain and lucerne hay in respective ratios of 80 : 20 : 0 [metabolisable energy (ME) = 7.4 MJ/kg DM, crude protein = 40 g/kg DM; ‘R1’] or 55 : 20 : 25 (ME = 8.2 MJ/kg DM, crude protein = 65 g/kg DM; ‘R2’). Rations were offered daily in a constant quantity that supplied ~80% maintenance energy requirements at the start of the experiment. Sheep fed R2 retained 0.7 kg more on average than those fed R1 (P < 0.01) after 20 days under experimental conditions with a mean weight change of –0.089 kg/day for R1 and –0.055 kg/day for R2 (P < 0.01). Sheep fed R1 experienced a sustained loss in digestive function over time, with ration DM digestibility decreasing by 0.56% per day (P < 0.01, R2 = 0.65), and MJ of ME per kg of ingested DM (M/D) decreasing by 0.06 MJ/kg DM per day (P < 0.001, R2 = 0.98). The mean M/D of R1 had fallen to 6.1 after 20 days (P < 0.01). The mean DM digestibility and M/D observed in R2-fed animals remained comparatively stable, with no statistically significant differences between starting and finishing values (P > 0.05). The results indicate that the capacity for underfed Tan weaner sheep to absorb energy from low protein rations typical of winter rapidly degrades and that the lucerne hay in the diet prevented this decline. Furthermore, these findings demonstrate that conserving lucerne for inclusion in winter rations is a potential strategy for smallholder farmers to maintain the digestive efficiency of Tan sheep during sustained underfeeding contributing to greater retention of liveweight on restricted diets.

The objective of the three studies reported here was to examine the grazing preference and diet selection of lambs for plantain (Plantago laceolata), chicory (Cichorium intybus L.) and red clover (Trifolium pratense) compared with New Zealand’s conventional ryegrass (Lolium perenne) pasture. Study One investigated the diet selection of lambs for 7 days at the beginning of March, using transects with tagged plants on a mixed plantain, chicory and red clover sward. Study Two was an outdoor preference experiment conducted in both March and May by observation of lambs on adjacent monocultures of plantain, chicory and red clover. Study Three was an indoor feeding trial that aimed to determine the intake rate and relative preference of weaned lambs for two herbages (chicory and plantain), two legumes (lucerne and red clover) and ryegrass pasture, in both spring (November) and summer (March). Study One determined that when grazing the mixed sward for a period of 7 days, the mean day that lambs commenced grazing red clover, chicory and plantain was Day 1.6 ± 0.1, 4.8 ± 0.2 and 6.2 ± 0.2, respectively, with significant (P < 0.05) differences between all species. In relation to preference as observed in Study Two, more lambs (P < 0.05) were seen to be grazing red clover at any time, and more lambs were grazing chicory (P < 0.05) than plantain. There was, also an interaction of season with preference, with plantain becoming more acceptable (P < 0.05) to the lambs in May (late autumn) versus March (early autumn). In Study Three, the term ‘preference’ refers to the natural logarithm of the ratio of amounts eaten between the forage being tested and the alternative forage offered simultaneously. This was established in triplicate by offering pairs of all the plant species side by side to individually penned lambs. The results indicated that plantain was consumed at a similar rate (P > 0.05) to that of ryegrass, whereas red clover and chicory had higher voluntary feed intakes, likely due to lower fibre content. The intake rate of chicory was greater in summer than spring and may be related to increased palatability due to the increased water-soluble carbohydrate content of chicory in summer. Regardless of season, average preference for red clover was always higher (P < 0.05) than that of chicory, plantain and ryegrass. Plantain was considerably less preferred in summer than spring. Differences in diet selection and preference may offer a unique opportunity to manipulate utilisation of pastures using a diverse range of plant species.

In sheep, maternal nutrition can affect the offspring’s milk production at its first lactation and the grand-offspring’s liveweight to weaning. However, this apparent developmental programming effect on milk production and grand-offspring liveweight has not persisted. Therefore, the aim of the present study was to determine if nutrition of the programmed ewe in mid- to late pregnancy affected this response. Developmentally programmed ewes (G1) that had been born from dams (G0) offered submaintenance, maintenance or ad libitum feeding levels from Day 21 to Day 50 of pregnancy and then either pregnancy maintenance or ad libitum to Day 140 were used for this study. These ewes were offered one of two pastoral-based pregnancy nutritional treatments (controlled vs unrestricted) from Day 76 of pregnancy until lambing. Pre- and post-herbage masses of the unrestricted treatment (2181 ± 47.6 and 1431 ± 24.6 kg DM/ha, respectively), were greater (P < 0.05) than the controlled treatment (1164 ± 31.6 and 819 ± 16.0 kg DM/ha, respectively). At Day 71 of pregnancy, there were no differences (P > 0.05) in G1 liveweight (70.2 ± 0.8 vs 70.3 ± 0.8 kg for controlled and unrestricted feeding, respectively), or body condition scores (2.5 ± 0.06 vs 2.5 ± 0.05) between pregnancy nutritional treatments. In late pregnancy, unrestricted G1 ewes were heavier (P < 0.05, 97.4 ± 1.0 vs 86.8 ± 1.0 kg) and had greater (P < 0.05) body condition scores (3.4 ± 0.06 vs 2.5 ± 0.06) and back-fat depths (8.0 ± 0.3 vs 5.9 ± 0.03 mm) than controlled nutritional treatment ewes. There were no interactions (P > 0.05) between grand-dam feeding levels and ewe nutritional treatment on lamb (G2) liveweights at birth or in lactation. This indicates that under the conditions of the present study, nutrition of the G1 ewe did not affect the expression of the developmental programming effect. Further studies might be warranted to determine the causes of this inconsistency in grand-offspring liveweight. Nutrition of the G1 ewe had a minor effect (P < 0.05) on G2 lamb birthweight and liveweight in early lactation but not (P > 0.05) in late lactation or on lamb survival. These findings indicate there is no little to no benefit to the lamb until weaning from offering ewes pre- and post-grazing masses above ~1200 and 800 kg DM/ha, respectively, in mid- to late pregnancy.

Little is known about the long-term impacts of selecting progeny born to ewe-lambs (EL) as replacements. This study investigated whether being born to a ewe-lamb affected the liveweight, milk production and reproductive performance of the offspring to 3 years of age in comparison with those born to adult multiparous ewes. Twenty-seven and 28 single-born Romney ewe progeny (G1) were born to either EL or to adult ewes (AE), respectively. Offspring born to ewe-lambs (ELG1) were lighter (P < 0.001) at birth and up to 12 months of age compared with offspring born to adult ewes (AEG1). Reproductive performance of AEG1 and ELG1 did not differ in regards to puberty attainment, pregnancy rate and number of fetuses. First lactation milk production, fat, crude protein, total protein, casein, lactose and total solids yield did not differ (P > 0.05). The second generation offspring born to ELG1 and AEG1 did not differ in birthweight in the first parity, but it did differ in the second parity and those lambs born to ELG1 were heavier from birth to weaning compared with those lambs born to AEG1. Combined, these results indicate, in the animals used in our study that productive performance of ewes born to EL does not differ to 3 years of age to that of ewes born to AE.

Maternal nutrition affects fetal development, with potential lifelong consequences. The study reported here compared the anatomical development (dimensions and organs) of twin fetuses at Day 140 of gestation, from 58 twin-bearing ewes fed at one of three different nutritional treatments in early pregnancy [Day 21–50, Low (LD21–50) versus Medium (MD21–50) versus High (HD21–50)] and one of two different nutritional treatments in mid- to late pregnancy (Day 50–140, Medium (MD50–140) versus High (HD50–140)]. There were no effects (P > 0.05) of either early or mid- to late pregnancy nutrition on placental weight and fetal bodyweight or size measurements at Day 140. Semitendinosus muscles from LD21–50-HD50–140 fetuses were heavier (P < 0.05) than those from LD21–50-MD50–140 and HD21–50-HD50–140 fetuses, and fetuses from LD21–50 dams had lighter (P < 0.05) mammary glands compared with those from MD21–50 and HD21–50 dams, even after adjustment for fetal weight. Maternal nutrition also affected (P < 0.05) the weights of the fetal thyroid and brain. These results suggest that farmers can limit ewe nutrition in early pregnancy with only minor effects on the fetus. To investigate potential lifetime effects, a larger cohort of these animals is currently being monitored.

Twin- and triplet-born lambs are smaller and lighter at birth than singletons and remain so until at least 1 year of age. However, there is little evidence in the literature to demonstrate if these smaller/lighter twin- and triplet-born lambs are metabolically different to singletons later in life. Additionally, many studies have demonstrated that dam nutrition during the periconceptual period can program the fetus in utero, influencing development, growth and performance later in life. However, little is known regarding the impact of differing levels of maternal nutrition before the periconceptual period, during the period of preantral follicle development. This study aimed to determine if dam pre-breeding nutrition (High versus Maintenance, 113–71 days pre-breeding) and birth rank (single versus twin versus triplet) affected the metabolic responses of ewes at 18 months of age, to an intravenous glucose (0.17 g/kg liveweight) (GTT) and insulin (0.15 IU/kg liveweight) (ITT) tolerance test. Dam pre-breeding nutrition had no effect (P > 0.05) on glucose and insulin responses to GTT, or glucose and cortisol responses to ITT. However, before both GTT and ITT, ewes born to High-fed dams had greater (P < 0.05) β-hydroxybutyrate (β-HBA) baselines than those born to Maintenance-fed dams, and also had greater (P < 0.05) maximum β-HBA change in response to both GTT and ITT. Birth rank tended (P = 0.06) to affect maximum glucose concentration change in response to glucose administration, with twin-born ewes having a greater increase in glucose compared with both singletons (P = 0.06) and triplet-born (P < 0.05) ewes in response to a glucose challenge. Insulin area under the curve 0–120 min after glucose administration of twin-born ewes was lower (P = 0.05) than both single- and triplet-born ewes. Prior to ITT, baseline β-HBA concentrations of single-born ewes were lower (P < 0.05) than triplet-born ewes. Single-born ewes had a reduced (P < 0.05) decrease in β-HBA change compared with twin- and triplet-born ewes in response to ITT. In summary, this study showed little difference in glucose and insulin metabolism of single-, twin- and triplet-born lambs at 18 months of age. However, the level of dam nutrition 113–71 days pre-breeding appears to have lasting effects on β-HBA metabolism in ewe progeny. The next step is to determine if these metabolic differences result in any measurable animal performance differences, as this would have implications for feeding regimes of ewes before mating and selection of appropriate ewe progeny for use as replacement animals.

Nutrition of the ewe at various stages of pregnancy is known to affect ewe and offspring performance. However, little is known regarding the potential interactions among differing maternal nutrition regimens in early and mid–late pregnancy. The objective of the present study was to examine the effects and potential interactions of three pastoral nutritional treatments from Day 21 of pregnancy (P21) to P50 (Sub-maintenanceP21–50 (total liveweight change achieved, SMP21-50, –0.15 ± 0.02 kg/day) v. MaintenanceP21–50 (MP21-50,–0.02 ± 0.02 kg/day) v. Ad libitumP21–50 (AdP21-50,0.15 ± 0.02 kg/day) and two pastoral nutritional treatments from P50 to P139 [MaintenanceP50–139 (designed to match change in conceptus mass, total liveweight change achieved, 0.19 ± 0.01 kg/day) v. Ad libitumP50–139 (0.26 ± 0.01 kg/day)] on 382 twin-bearing ewes and their offspring until 91 days after the mid-point of lambing (L91). Ewe liveweight and condition scores in pregnancy and lactation, and lamb liveweights, indices of colostrum uptake and survival were recorded. There were no interactions between nutritional periods for lamb liveweight, apparent colostrum intake and survival, and ewe liveweight, condition score and total weight of lamb per ewe at the end of the study. At L91, ewe nutritional treatment during P21–50 or P50–139 had no effect on either ewe liveweight or body condition score. Ewe nutritional treatment during P21–50 had no effect on lamb birthweight. Lambs born to AdP50–139 ewes were lighter (P < 0.05) than those born to MP50–139 ewes (5.32 ± 0.04 v. 5.48 ± 0.04 kg, respectively). Ewe nutritional treatment during P21–50 or P50–139 had no (P > 0.05) effect on indices of colostrum uptake in lambs at 24–36 h of age. At L91, ewe nutritional treatment during P21–50 or P50–139 had no effect on lamb liveweight, survival or total weight of lamb per ewe. In conclusion, although considerable differences in ewe liveweight were observed during pregnancy, the nutritional treatments had no effect on the production parameters measured at the end of the study. These results indicate, first, that farmers can use early pregnancy as a period to control ewe nutrition when ewes are offered at least pregnancy maintenance levels of nutrition in the mid–late pregnancy period and, second, that there is no advantage from offering twin-bearing ewes a level of nutrition above their pregnancy maintenance requirements in mid–late pregnancy.

The potential of mixed herb and legume pastures to increase post-weaning growth rates of lambs in comparison to ryegrass-based pastures was evaluated. Unrestricted allowances of pasture treatments were offered to weaned, Romney lambs in consecutive autumns of 2007 and 2008. In Experiment 1 (2007), 300 ewe lambs were allocated for 64 days to one of four permanent sward mix treatments; chicory, plantain, red clover and white clover [herb/clover (n = 75)]; plantain, perennial ryegrass and white clover [plantain/pasture (n = 75)]; tetraploid perennial ryegrass and white clover [new pasture (n = 75)]; or diploid perennial ryegrass, other grass species and white clover [old pasture (n = 75)]. In Experiment 2 (2008), the first three pasture treatments from Experiment 1 were re-used (‘old pasture’ not used) with 168 wether lambs allocated for 35 days; herb/clover (n = 56); plantain/pasture (n = 56); and new pasture (n = 56). Unfasted liveweights of all lambs were recorded at weekly intervals and before slaughter. A sub-sample of 78 lambs from Experiment 2 was slaughtered to obtain the carcass weights, tissue depth (11 cm from the spine over the 12th rib) and commercial meat percentages. At the conclusion of Experiment 1 the herb/clover treatment lambs were heavier than the new pasture and plantain/pasture treatment lambs, which were heavier than the old pasture treatment lambs (47.4 vs 41.5 vs 41.5 vs 39.6 ± 0.4 kg, respectively) (P < 0.05). At the conclusion of Experiment 2 the herb/clover treatment lambs were heavier than the new pasture treatment lambs, which were heavier than the plantain/pasture treatment lambs (35.6 vs 32.8 vs 28.8 kg ± 0.4, respectively) (P < 0.05). In Experiment 1 a higher percent of herb/clover treatment lambs grew faster than 200 g/day (P < 0.001) than of the pasture/plantain, new pasture and old pasture treatment lambs (87 vs 4 vs 3 vs 0 percent, respectively). In Experiment 2 only the herb/clover lambs (71%) grew faster than 200 g/day (P < 0.05). In Experiment 2 herb/clover treatment lambs had heavier (P < 0.05) final carcass weight (15.7 ± 0.20 vs 14.8 ± 0.38 vs 14.6 ± 0.27 kg) compared with the plantain/pasture and new pasture lambs, respectively. It was demonstrated that a herb/clover mixed sward can increase post-weaning lamb liveweight gains during unrestricted feeding conditions compared with traditional perennial ryegrass-based pastures.

In an effort to increase the number of lambs produced per ewe’s productive lifetime in New Zealand, an increasing number of ewe lambs (8–9 months old) are being bred. This, in turn, results in an increased proportion of second-parity 2-year-old ewes in New Zealand’s breeding flock, rather than the more usual first-parity 2-year olds. The longer-term effects of dam parity on resulting ewe progeny are of interest and few studies have examined this. The present study was designed to determine whether parity (first or second) of Romney 2-year-old dams had any effect on the metabolic function of their single- and twin-born and reared ewe lamb progeny at 10 months of age. Ten-month-old, single and twin ewe lamb progeny born to first- or second-parity dams (n = 8 per group) were catheterised and given intravenous glucose (0.17 g/kg liveweight) (GTT), insulin (0.15 IU/kg liveweight) (ITT) and epinephrine (1 μg/kg liveweight) (ETT) tolerance tests to assess their glucose and fat metabolism and adrenal function. Rearing rank reduced (P < 0.05) the insulin response of twins to a glucose challenge, but increased (P < 0.05) their glucose response to an insulin challenge. Offspring from first-parity dams had higher (P < 0.05) basal plasma concentrations of cortisol and cortisone, whereas their cortisol/cortisone responses to an insulin challenge were unaffected by either dam parity or rearing rank. Neither dam parity nor rearing rank appeared to influence responses to an epinephrine challenge. The present study suggests that both dam parity and rearing rank alter the glucose and insulin metabolism of the offspring, which may have longer-term impacts on the growth and reproductive efficiency of the animal.