Early life intervention is important to shape the gut microbiome profiles of adult animals due to the tremendous alteration of diet components.  Nevertheless, there is still no unified understanding about its long-term effects in lambs.  In this study, sixty 20-day-old lambs were assigned into ewe-rearing (ER) and artificial-rearing (AR) treatments to evaluate the effects of AR strategy on ruminal microbiota, fermentation, and morphology of pre-weaning lambs (from 20 to 60 days of age) and its long-term effects in the fattening stage (from 61 to 180 days of age).  During the pre-weaning stage, ER lambs were breastfed and supplemented starter, while AR lambs were artificially fed with milk replacer and starter.  During the fattening stage, all lambs in both treatments were fed with the same fattening diets.  At 60, 120 and 180 days of age, 6 lambs from each group were slaughtered to collect rumen content and tissue samples.  Compared with ER lambs, the dry matter feed intakes of AR lambs increased (P<0.05) from 20 to 180 days of age, companying an increased average daily gain (ADG) from 61 to 120 days of age (P<0.05) and from 121 to 180 days of age (0.05<P<0.1).  Although there was no difference in short-chain fatty acid (SCFA, including acetate, propionate, and butyrate) between treatments before weaning (P>0.05), it was higher (P<0.05) in AR lambs compared with ER lambs at the fattening stage.  The rumen keratin layer of AR lambs was thinner (P<0.05) than that of ER lambs.  Along with lamb growth from 60 to 180 days of age, the differences in rumen bacterial diversity between AR and ER treatments grew more distinct (P<0.05).  Compared with ER lambs, AR lambs increased (P<0.05) rumen bacteria abundance, such as phylum Spirochaetes and genus Treponema at 60 days of age, phylum Actinobacteria and genus Succiniclasticum at 120 days of age, and phylum Proteobacteria at 180 days of age, but decreased genus Selenomonas from 60 to 180 days of age, and Anaerovibrio at 180 days of age.  In summary, the early interventions before weaning could improve dry matter feed intake of lambs, which triggered robust rumen development and produced positive long-term effects on rumen fermentation and noticeable weight gain of fattening lambs.  It suggests that the artificial rearing strategy is effective in improving rumen fermentation and microbial maturity of intensive fattening lambs.

China has the world’s largest sheep flock and the largest producer of sheep meat by far.  However, the nutrient requirements have not been systemically studied and there is a lack of knowledge of nutrient requirement for meat-type sheep in China.  Since 2008, the nutrient requirements of meat-type sheep in China has been systematically investigated.  In this review, we introduced the history of studies of nutrient requirements of meat-type sheep in China, summarized the recent advances in nutrient requirements of meat-type sheep, and highlighted the future directions of researches on nutrient requirements of meat-type sheep in China.

The importance of nutrient provisions and weaning methods for calves has been well established over the past few years, while as increasing interest has focused on contribution of animal behavior and their overall performance in production regimes.  The present study investigated the effects of feeding methods and space allowance on growth performance, individual and social behaviors in Holstein calves.  Twenty-four Chinese Holstein male and female calves were allocated to either an individual or group of 6 and fed either with a bucket or a teat.  Milk replacer, calf starter, and Chinese wildrye were offered during the experiment.  A fecal index used in the present study was defined as the total fecal scores/total number of calves in each treatment.  The results showed that there was no significant difference among the 4 treatments in terms of feed intake, body weight, average daily gain, and fecal index.  For the feeding behaviors, the ingesting milk time and ingesting milk rate were significantly affected by space allowance, while the feeding methods showed a significant influence on the bunting behavior of the calves.  There was no significant difference among the 4 treatments in terms of licking fixtures, self-grooming, and lying down behaviors, irrespective of the feeding method or space allowance.  However, sucking an empty bucket or the teat was significantly affected by the feeding method.  Several selected group behaviors were examined in the present study, and similar values for sniffing the other calves, social grooming, and cross-sucking behaviors were observed.  Overall, the present study demonstrated that different feeding methods and space allowances had a significant effect on the feeding behavior of calves, while the feed intake, growth performance, health condition, individual and group social behaviors were not significantly influenced.  Furthermore, under intensified production systems, Holstein calves raised in a group may obtain a similar production performance, thus reducing management input and profitability compared with those kept individually.  However, there may be competition during the feeding period.

The net protein (NP) and metabolizable protein (MP) requirements of Dorper crossbred female lambs from 20 to 35 kg body weight (BW) were assessed in a comparative slaughter trial.  Thirty-five Dorper×thin-tailed Han crossbred lambs weaned at approximately 50 d of age ((19.1±2.37) kg of BW) were used.  Seven randomly selected lambs were slaughtered at the beginning of the trial as baseline group (BL).  An intermediate group of seven randomly selected lambs fed ad libitum (AL) intake was slaughtered when the lambs reached an average BW of 28.6 kg.  The remaining 21 lambs were allotted randomly to three levels of dry matter intake: AL or restricted to 70 or 40% of the AL intake.  All lambs were slaughtered when the sheep fed AL intake reached 35 kg of BW.  Total body N and N retention were determined.  The results showed that the maintenance requirements for NP and MP were 1.75 and 3.37 g kg^–1 metabolic shrunk body weight (SBW^0.75), respectively.  The partial efficiency of protein use for maintenance was 0.52.  The NP requirements for growth ranged from 10.9 to 42.4 g d^–1 for the lambs gaining 100 to 350 g d^–1 from 20 to 35 kg BW.  The partial efficiency of MP for growth was 0.52.  In conclusion, the NP and MP requirements for the maintenance and growth of Dorper crossbred female lambs were lower than those reported by AFRC (1993) and NRC (2007) recommendations.

Two feeding patterns of the segregated weaning or grazing in the pasture are carried out worldwide in animal production. To investigate the difference of growth performance and rumen microorganism population related to methane metabolism in the two feeding patterns, three groups of lambs (70 in total) were used: Weaning at 21 days old and being subjected to high-concentration diets (3WK group with 20 lambs), weaning at 35 days old and being subjected to high-concentration diets (5WK group with 20 lambs), or grazing at pasture with the nursing mother (Grazing group with 30 lambs). The growth performance, pH value of rumen content, and the rumen microbes were investigated during weaning period and fattening period with approximately 3 months. Our results showed that lambs in 3WK and 5WK groups demonstrated a better growth performance than the lambs in Grazing group, but no significant difference was observed in the pH value between the three groups (P>0.05). The total rumen bacterial population of the Grazing lambs was significantly lower than that of 3WK lambs (P<0.05) and 5WK lambs (P<0.05); however, the population of methanogens was 4.2- and 2.7-fold lower in the 3wk (P<0.05) and 5wk (P<0.05) lambs compared with Grazing lambs, respectively; protozoa were also 3.5- and 3.4-fold lower in the 3WK (P<0.05) and 5WK (P<0.05) lambs, respectively. The results revealed that segregated weaning lambs may have better growth performance, and reduce methane-producing microbes.

A comparative slaughter trial was conducted to determine the net mineral requirements for maintenance and growth of Dorper crossbred female lambs raised from 20 to 35 kg of body weight (BW). Thirty-five Dorper×thin-tailed Han crossbred female lambs of (20.3±1.14) kg BW were used: 7 lambs were randomly chosen and slaughtered at the beginning of the experiment as the baseline group for measuring the initial body composition; another 7 lambs were randomly chosen and offered a pelleted mixed diet ad libitum and slaughtered at (27.0±0.73) kg BW; the remaining 21 lambs were randomly divided into 3 groups of 7 animals each and subjected to the same diet either ad libitum or at 70 or 40% of ad libitum intake. The 21 lambs were fed in 7 slaughter groups, with each group consisting of one lamb from each treatment (ad libitum, 70 or 40% of ad libitum intake). The 3 groups were slaughtered when the sheep fed ad libitum attained (33.8±0.52) kg of BW. The body composition of five minerals (Ca, P, Na, K, and Mg) was determined. The net mineral requirements for maintenance were 35.01, 25.18, 9.30, 31.35, and 2.03 mg kg–1 empty BW (EBW) for Ca, P, Na, K, and Mg, respectively, and the net growth requirement per kg of EBW gain ranged from 9.73 to 8.87 g of Ca, 5.83 to 5.27 g of P, 1.73 to 1.63 g of Na, 3.73 to 4.08 g of K, and 0.26 to 0.25 g of Mg for Dorper crossbred lambs in China, respectively. The estimates of mineral requirements with Dorper crossbred lambs in the current study were not consistent with the recommendations from previous studies.

This study aimed to investigate the effects of dietary supplementation of yeast β-glucan on the nutrient digestibility and serum profiles in pre-ruminant Holstein calves. Forty-two neonatal Holstein calves ((39.6±4.2) kg) were randomly allotted to six groups, and each was offered one of the following diets: a basal diet (control) or the basal diet supplemented with 25, 50, 75, 100 or 200 mg of yeast β-glucan kg–1 feed (dry matter basis). The basal diet consisted of a milk replacer and a starter feed. The trial lasted for 56 d. Two digestibility trials were conducted from d 14 to 20 and from d 42 to 48. Blood samples were collected on d 0, 14, 28 and 42 for serum profile analyses. On d 56, three calves from each group were slaughtered, and intestinal samples were collected to assess the villous height, crypt depth and mucosal thickness. Although feed intake was not affected by dietary treatment (P>0.05), the average daily gain (ADG) and gain-to-feed ratios were higher (P<0.05) for the calves fed 75 mg of yeast β-glucan kg–1 feed than those in the other groups. The supplementation of yeast β-glucan at 75 mg kg–1 feed increased the apparent digestibility of dry matter (DM), crude protein (CP), ether extract (EE), and phosphorus (P) (P<0.05) and the ratio of intestinal villous height to crypt depth (V/C) (P<0.05) when compared with the control group. No effects of yeast β-glucan on the serum concentrations of total protein (TP), albumin (ALB), serum urea nitrogen (SUN) and glucose (GLU) were observed (P>0.05). Compared with the control group, supplementation of yeast β-glucan decreased (P<0.05) the serum concentrations of triglycerides (TG) and total cholesterol (TC). The serum concentration of immunoglobulin G (IgG) and immunoglobulin M (IgM) increased quadratically (P<0.05), whereas the serum concentration of immunoglobulin A (IgA) was unaffected by dietary treatments (P>0.05). The supplementation of yeast β-glucan stimulated the enzymatic activity of alkaline phosphatase (ALP) (P<0.05) compared with the control group. The lysozyme (LYZ) concentration increased quadratically (P<0.05) with increasing yeast β-glucan levels. The results suggested that dietary supplementation of yeast β-glucan at 75 mg kg–1 feed improved nutrient digestibility, enhanced immunity by increasing the immunoglobulin concentration and stimulating ALP, and exerted no adverse effects on metabolism in pre-ruminant calves.

This experiment was conducted to investigate the energy requirement of Dorper×thin-tailed Han crossbred ewes during non-pregnancy and lactation. Fifteen ewes after parturition were randomly assigned to three treatments: ad libitum (100%) feed intake and 80 or 60% ad libitum intake, and another nine non-pregnant ewes were assigned to a blank control group. Digestibility trials were performed in the non-pregnant ewes and in the lactating ewes on the 20th, 50th, and 80th d of lactation. In parallel with the digestibility trial, a respirometry experiment was conducted to determine the methane and carbon dioxide production with an open-circuit respirometry system that was equipped with respiratory chambers. The net energy (NE) and metabolizable energy (ME) requirements for maintenance and growth were calculated using the carbon and nitrogen balance method. The results revealed that the carbon (C) and nitrogen (N) excretions and energy losses at faeces and urine, as well as the output of methane and CO2, increased significantly with decreasing feed intake (P<0.01). The apparent digestibilities of C in the stages of non-pregnancy and early, middle and late lactation were 55.8–58.3%, 62.5–73.8%, 64.8– 71.3%, and 61.7–65.0%, respectively, and the apparent digestibilities of N were 45.2–51.3%, 73.7–82.7%, 72.8–80.5%, and 73.6–76.5%, respectively. The corresponding energy apparent digestibilities were 52.0–56.3%, 60.7–76.6%, 61.0–68.8%, and 61.4–67.7%, respectively. The ME/DE (digestible energy) values were 79.5–85.9%, 79.4–83.5%, 81.0%–85.3% and 78.6–82.9%, respectively. The maintenance requirements of NE, ME, and the efficiencies of ME utilisation for maintenance during the stages of non-pregnancy and early, middle and late lactation were 215.5, 253.1, 247.7, and 244.7 kJ kg–1 BW0.75 d, and 372.4, 327.1, 320.9, and 362.0 kJ kg–1 BW0.75 d, and 0.58, 0.77, 0.77, and 0.68, respectively. The ME requirement for the growth of non-pregnant ewes was 31.3 MJ kg–1 BW gain.

A comparative slaughter trial and a metabolism trial were conducted to determine the requirement of net energy (NE) and metabolizable energy (ME) by the crossbreed of German Mutton Merino×Inner Mongolia Merino for fattening from 35 to 50 kg of body weight (BW). 49 crossbred female lambs ((33.9±2.3) (SD) kg BW) of German Mutton Merino×Inner Mongolia Merino were used. 34 lambs were randomly chosen for comparative slaughter, which were offered an identical mixture diet (concentrate:roughage=55:45) at 100, 75 or 55% of ad libitum intake, whereas the remainders were used in the metabolism trial to evaluate the ME of the diet after methane production was measured by open-circuit respirometry. As feed intake decreased from 100 to 75 and 55% of ad libitum intake, the apparent digestibility of dry matter (DM) linearly increased (P=0.010) from 60.8 to 63.6 and 66.9%, respectively, and methane production decreased from 52.1 to 44.3 and 39.9 L d-1, respectively, but the ratio of methane energy to gross energy intake increased linearly (P=0.010) from 8.20 to 8.96 and 10.97%, respectively. Consequently, the ME values of the diet increased from 9.35 to 9.64 and 9.85 MJ kg-1 DM, respectively. The NE requirement for maintenance (NEm) was 255 kJ kg-1 BW0.75, and the ME requirement for maintenance (MEm) was 352 kJ kg-1 BW0.75, with a partial energy efficiency for maintenance (km) of 0.72. The NE requirement for growth (NEg) ranged from 1.26 to 4.66 MJ d-1 as average daily gains increased from 100 to 300 g d-1, with a partial energy efficiency for growth (kg) of 0.45. These results indicated that the NEg required by crossbred female lambs of German Mutton Merino×Inner Mongolia Merino was lower than the recommendation of the American or British nutritional system.