Lamb Growth Research Articles

Animal performance over 16 years after implementing a lucerne grazing system on Bog Roy Station - a case study

In 2023, the animal performance data for Bog Roy station show 151 t weaned lamb is being produced from 4272 ewes plus 9.0 t from hogget lambs. The ability to mate merino hoggets has resulted from increased feed supply that means mixed age ewes are now consistently averaging 65.6±1.17 kg/hd at mating (2019-2023). This has enabled an emphasis on two-tooth weight at mating, which has also increased 0.74±0.14 kg/hd/yr (R2 = 0.64) from 52 kg/hd in 2012 to 61 kg/hd in 2023. Consequently, scanning is consistently ~167±1.59% for the mixed age ewes (2012-2023) and increased from 113% (2008) to 154% (2023) in the two-tooths. Lamb wastage for the mixed age ewes has decreased 0.70±0.08%/yr (R2 = 0.88) to 15% in 2023 and, although more variable (R2 = 0.13), the wastage in two-tooths has also reduced from 32% (2014) to 21% (2023). Lamb wastage is negatively related to two-tooth weight at set-stocking, so feeding young stock is a priority. Since 2016, pre-weaning merino lamb growth rates have averaged 286±4.39 g/hd/d with weaning now at 79.3±2.56 days. This consistency coincided with the addition of 210 ha of feed under pivot irrigation that was initially sown in red and white clover and is now in lucerne/grass mixes. The additional feed has meant wool production has remained constant throughout the 15 years of pasture development. Cow numbers have been used to buffer the changes in pasture supply as the dryland and pivot development occurred. These have now increased to their highest level since the development began. The major change in farm income has resulted from the earlier sale of more lambs at a higher average price because they are heavier due to the extra feed. This unique long-term dataset of on-farm performance provides a commercial example of transformational change that has resulted from changes in the farm system, driven by direct feeding of dryland lucerne and irrigation development focused on growing young stock in this 420 mm rainfall environment.

Evaluation of an engineered vascular graft exhibiting somatic growth in lambs to model repair of absent pulmonary artery branch

BackgroundGrowth is the holy grail of tissue implants in pediatrics. No vascular graft currently in use for surgical repairs of congenital heart defects has somatic growth capacity.MethodsBiologically-engineered grafts (6 mm) grown from donor ovine fibroblasts in a sacrificial fibrin gel were implanted into the left pulmonary branch of 3-month old lambs for 3, 6, and 18 months. A control group of Propaten® PTFE grafts was implanted for 6 months.ResultsThe engineered grafts exhibit extensive site-appropriate recellularization after only 3 months and near-normal increase of diameter from the preimplant value of 6 mm to 12.9 mm and also a doubling of length from 6.0 mm to 13.0 mm at 6 months (n = 3) associated with apparent somatic graft growth (collagen content increase of 265% over 18-month, n = 2), along with excellent hemodynamics and no calcification, in contrast to the Propaten® grafts. The left-right flow distribution is nearly 50–50 for the engineered grafts at 6 months (n = 3) compared to about 20–80 for the Propaten® grafts (n = 3), which have less than one-half the diameter, a 6-fold higher pressure gradient, and stunted vascular development downstream of the graft. The engineered grafts exhibit a stable diameter over months 12–18 when the lambs become adult sheep (n = 2).ConclusionsThis study supports the use of these regenerative grafts with somatic growth capacity for clinical trial in patients born with a unilateral absent pulmonary artery branch, and it shows their potential for improving development of the downstream pulmonary vasculature.

Effects of Active Dry Yeast Supplementation in In Vitro and In Vivo Nutrient Digestibility, Rumen Fermentation, and Bacterial Community.

This study assessed the impact of active dry yeast (ADY) on nutrient digestibility and rumen fermentation, using both in vitro and in vivo experiments with lambs. In vitro, ADYs were incubated with rumen fluid and a substrate mixture to assess gas production, pH, volatile fatty acid (VFA) profiles, and lactate concentration. In vivo, Hu lambs were randomly assigned to five dietary treatments: a control group and four groups receiving one of two dosages of either Vistacell or Procreatin7. Growth performance, nutrient digestibility, rumen fermentation parameters, and bacterial community composition were measured. Pro enhanced the propionate molar proportion while it decreased the n-butyrate molar proportion. Vis reduced the lactate concentration in vitro. In the in vivo experiment, Vis increased the propionate molar proportion and the Succinivibrionaceae_UCG-001 abundance while it decreased the n-butyrate molar proportion and the Lachnospiraceae_ND3007 abundance. Additionally, Vis showed a greater impact on improving the NDF digestibility and total VFA concentration in vivo compared to Pro. Overall, the effects of ADYs on rumen fermentation were found to vary depending on the specific ADY used, with Vis being the most suitable for lamb growth. It was observed that Vis promoted propionate fermentation and Succinivibrionaceae_UCG-001 abundance at the expense of reduced n-butyrate fermentation and Lachnospiraceae_ND3007 abundance. Importantly, differences were noted between the outcomes of the in vitro and in vivo experiments concerning the effects of ADYs on rumen fermentation, highlighting the need for caution when generalizing batch culture results to the in vivo effects of ADYs.

Influence of sire plane of nutrition and targeted body weight gain on ewe lamb growth, glucose metabolism, and ovarian reserve.

Rambouillet rams were managed on either a positive (POS; gain 12% body weight [BW]; n = 8), maintenance (MAINT; maintain BW; n = 8), or negative (NEG; lose 12% BW; n = 8) plane of nutrition before breeding. Rams were bred to ewes (n = 10 per ram) that were managed similarly throughout gestation, and lambs were fed a common diet postnatally. Two ewe lambs (7.6 ± 0.02 months of age, BW = 47.1 ± 1.17kg) from each sire were selected and within pair, randomly assigned to be managed for a moderate (MOD, 0.11kg/d; n = 23) or accelerated (ACC, 0.20kg/d; n = 22) rate of gain for 56 d. Ewe lamb BW was recorded on a weekly basis and blood was collected on d 0, 28, and 56 for analysis of insulin-like growth factor 1 (IGF-1), triiodothyronine (T3), thyroxine (T4), glucose, blood urea nitrogen (BUN), and non-esterified fatty acids (NEFA). Intravenous glucose tolerance tests (IVGTT) were conducted from d -7 to -4 and d 57 to 64. A unilateral ovariectomy was performed and ovarian follicles were staged and counted macro and microscopically. Sire treatment × day and ewe treatment × day interactions were present for BW (P ≤ 0.05), where POS had slower growth than MAINT and NEG, and tended (P = 0.10) to have reduced average daily gain (ADG) when managed at an accelerated rate of gain.By design, ACC had greater BW and ADG than MOD (P < 0.05). Concentrations of IGF-1 and T4 were greater in ACC than MOD (P ≤ 0.05), and NEG tended to have greater concentrations of IGF-1 than POS and MAINT (P = 0.08). At the first IVGTT, concentration of insulin was influenced by a sire treatment × time interaction (P ≤ 0.05), suggesting impaired secretion in NEG-sires ewes, but no differences in area under the curve (AUC) for glucose, insulin, or their ratio (P ≥ 0.11). No interactive effects of sire and ewe treatment (P ≥ 0.52) were observed at the second IVGTT, but insulin and insulin:glucose ratio were influenced by sire treatment × time (P ≤ 0.02), as NEG had greater insulin concentration at 60min than MAINT (P = 0.03) and greater AUC than POS and MAINT (P ≤ 0.04). No differences in ovary size, weight, or total counts of macro and microscopic follicles were observed (P ≥ 0.23). Ewes fed ACC had a greater number of small surface follicles (P = 0.02), whereas MOD tended to have a greater number of large surface follicles and tertiary follicles (P < 0.06). These findings suggest that paternal plane of nutrition influences female offspring physiology, particularly at varying growth rates.

Impact of early weaning and nutritional interventions on growth performance, digestive metabolism, and serum biomarkers in lambs: A biomechanical perspective

The aim of this study was to investigate the effects of early weaning and nutritional interventions on growth performance, nutrient digestion and metabolism, and serological indices of hu sheep lambs, with a view to providing a basis for the feasibility of early weaning of hu sheep lambs under conditions of supplemental milk replacer. Ninety neonatal hu sheep lambs were weaned at 21 days (n = 60) (divided into two groups: early weaned, EW; and resveratrol-fed, RSV) as well as 49 days (n = 30) (control group, CON) weaning, and the trial period was 90 days. The results showed that: 1) there was no significant difference (P &gt; 0.05) in the initial and final weights of the lambs, and the average daily gain (ADG) of the EW and RSV groups was significantly lower than that of the CON group (P &lt; 0.05) from 31 to 45 days of age. Early weaned lambs were more susceptible to weaning stress compared to late weaned lambs and the effect of nutritional intervention (feeding resveratrol) on lamb growth performance was not significant. 2) The apparent digestibility of crude protein (CP) in the experimental group was significantly lower than that of the control group (P &lt; 0.05), and the nitrogen intake, net protein utilization and protein biological value indexes of lake lambs in the experimental group were significantly different from those of the control group (P &lt; 0.05). 3) Early feeding of resveratrol was not significant in improving the digestive metabolism of nutrients. 4) Early weaning as well as the addition of resveratrol had a significant effect on the serum GLU and TC indexes of the lambs (P &lt; 0.05), but did not show a significant effect on any of the other indexes.

Dietary secoisolariciresinol diglucoside crude extract improves growth through modulating rumen bacterial community and epithelial development in lambs.

Flaxseed lignans, types of polyphenolic compounds, primarily consist of secoisolariciresinol diglucoside (SDG). Natural plant extracts are becoming increasingly important as feed for ruminant animals. An underutilized plant bioactive component, SDG shows promising benefits for young ruminant production. The objective of this study was to assess the impact of SDG on rumen fermentation using an in vitro rumen simulation technology. Additionally, we tested the effects of SDG (0.20 g kg-1 body weight) on rumen development and production performance of lambs in a production setting. The in vitro addition of 100 mg L-1 SDG demonstrated significant regulatory effects, with a notable decrease in the acetate/propionate ratio (P < 0.05). Feeding trials revealed that SDG significantly increased average daily feed intake and average daily weight gain (P < 0.05), and reduced the acetate/propionate ratio (P < 0.05). This led to a significant increase in the relative abundance of Eubacterium ruminantium (P = 0.038) and Butyrivibrio (P = 0.002). Furthermore, it promoted rumen development and upregulated the relative expression of mRNA of Cyclin E1 and CDK2 in rumen epithelial cells (P < 0.05). The SDG extract optimizes the composition of rumen microbiota and the development of rumen epithelial cells, promoting the growth of pre-weaning lambs. The SDG additive exhibits potential as a novel growth promoter for ruminant animals, offering a promising solution for sustainable livestock production. © 2024 Society of Chemical Industry.

288 Maternal fatty acid supplementation and its impact on dam and offspring performance

Abstract Fatty acid supplementation has multiple benefits to the offspring when supplemented to the dam during pregnancy; limited to no benefits to the dam have been documented. We hypothesized that maternal fatty acid supplementation during pregnancy would result in improved body weight (BW) and body condition score (BCS) in the ewes and improve lamb growth until weaning and male offspring growth following weaning when ewes were supplemented fatty acids. On d -8 of the study (35 d of gestation), all ewes were weighed, BCS was collected, and pregnancy status determined. Pregnant Targhee ewes (n = 83) were assigned to a treatment group based on age, BW, and BCS, to one of four treatment gr: 1) 22 g/ewe daily of Ca salts of saturated and monosaturated fatty acids based on palmitic and oleic acids (CON; EnerGII, Virtus Nutrition, LLC, Corcoran, CA); 2) 22 g/ewe daily of Ca salts of PUFA based on eicosapentaenoic (EPA) and docosahexaenoic (DHA) acids (ɷ-3, Strata; Virtus Nutrition LLC); 3) 22 g/ewe daily of Ca salts of PUFA based on linoleic acids (ɷ-6, Prequel; Virtus Nutrition LLC); or 4) 11 g/ewe of Ca-salts enriched with EPA+DHA (Strata) and 11 g/ewe of Ca-salts enriched with linoleic acid (Strata) daily (ɷ-3 + 6; Virtus Nutrition LLC). Fatty acid supplementation occurred from d 0 until d 88 of the study, and all ewes were fed grass hay. Ewe BW and BCS were recorded at d -8, 51, 93, and 240 of the study. Twenty-four hours after birth, lamb sex was identified and weighed (n = 136 lamb; CON = 33; ɷ-3 = 32; ɷ-6 = 36; ɷ-3 + 6 = 35). Lambs were weighed at d 175 and 240 (weaning) of the study (n = 86; CON = 22; ɷ-3 = 22; ɷ-6 = 21; ɷ-3 + 6 = 21). Body weight, BCS, and scrotal circumference (SC) were collected on all ram lambs at d 352, 380, and 408. No differences were observed in ewe BW or BCS at d -8, 51, or 93 of the study (P ≥ 0.26) between the treatment groups (Table 1). A treatment × day interaction was observed at d 240 of the study when ɷ-6 ewes had a greater (P = 0.03) BCS compared with group cohorts. No differences in lamb birth weight, lamb weight or average daily gain at d 175 or 240 of the study between treatment groups (P ≥ 0.25; Table 2). No differences were reported in ram lamb BW, BCS, or SC at d 352, 380, and 408 (P ≥ 0.31; Table 3). These results indicate that maternal fatty acid supplementation alters ewe BCS at the time of weaning; however, supplementation does not impact lamb growth from birth until weaning or ram lamb growth and scrotal circumference.

Succession of rumen microbiota and metabolites across different reproductive periods in different sheep breeds and their impact on the growth and development of offspring lambs

BackgroundThe microbiota and metabolites in the gastrointestinal tracts of female animals at different reproductive periods are very important to the growth, development, and health of themselves and their offspring. However, the changes in the gastrointestinal microbiota and metabolites throughout reproductive period of different sheep breeds and their effects on the growth and development of offspring lambs are still unclear. Hence, this study presents an assessment of the reproductive hormone levels, immune levels, rumen microbiota, and metabolites in Hu sheep and Suffolk ewes at different reproductive periods and their effects on the growth and development of offspring lambs.ResultsHu sheep and Suffolk during non-pregnancy, pregnancy, and lactation were used as the research objects to determine reproductive and immune indexes of ewes at different periods, analyze rumen microbiome and metabolome, and track the growth performance and development of offspring lambs. The results showed that the reproductive hormone and immune levels of Hu sheep and Suffolk underwent adaptive changes across different reproductive periods. Compared with non-pregnancy, the microbial energy metabolism and lipid metabolism function decreased during Hu sheep pregnancy, and energy metabolism function decreased during lactation. In Suffolk, energy metabolism, glycan biosynthesis, and metabolism function were enhanced during pregnancy, and the metabolism of cofactors and vitamins was enhanced during lactation. Prevotella increased in Suffolk during pregnancy and lactation (P < 0.05) and was positively correlated with the birth weight and body size of the lambs (P < 0.05). Moreover, the abundances of Butyrivibrio and Rikenellaceae_RC9_gut_group during pregnancy were positively correlated with the intestinal immunity of the offspring lambs (P < 0.05), thereby regulating the intestinal immunity level of the lambs. Metabolomic analysis revealed that the protein digestion, absorption, and amino acid metabolism of Hu sheep were enhanced during pregnancy, which provided amino acids for the growth and development of pregnant ewes and fetuses and was significantly correlated with the birth weight, body size, and intestinal immunity of lambs (P < 0.05). Simultaneously, there was an increase in acetate and propionate during the pregnancy and lactation period of both Hu sheep and Suffolk, providing energy for ewes during reproductive period. Moreover, the microbiota during the lactation period was significantly correlated with the milk quality and lambs daily gain (P < 0.05).ConclusionsThis study revealed the characteristic succession changes in the rumen microbiota and its metabolites at different reproductive periods in sheep breeds and their regulation of reproductive hormone and immune levels and identified their potential effects on the growth and development of offspring lambs. The findings provide valuable insights into the health and feeding management of different sheep breeds during the reproductive stage.Cnu7uEJBESQuA-vs1kGzfaVideo

Evidence for a constitutive cost of host resistance on body fat growth in ewe lambs from lines selected for resistance or susceptibility to experimental infections with Haemonchus contortus

Although benefits of selection for host resistance to gastro-intestinal nematodes have long been recognized, its costs on production traits remain unclear. A main difficulty when studying those costs is to disentangle genetic effects due to selection from plastic responses induced by infection. Putative costs of host resistance have been extensively investigated in growing sheep. However, while most of those studies have relied on live weight to assess body growth, more comprehensive assessments accounting for body composition are advocated to detect trade-offs. In this study we used 90 female lambs from lines divergently selected on resistance to Haemonchus contortus that we experimentally infected (n = 60) or not (n = 30) under controlled conditions. As those conditions were defined to enable uninfected lambs to fully express their growth potential, we sought to precisely identify the effects of selection for host resistance on health traits and on growth traits. We assessed muscular and fat growth based on repeated measurements with dorsal ultrasonography for all lambs on farm, and with whole-body computed tomography (CT) scans for a subgroup of 18 infected lambs. Lambs achieved a high growth rate, including infected ones despite their high worm burden (confirmed at necropsy in the subgroup). As expected, lambs from the resistant (R) line were less infected than those from the susceptible (S) line. However, the clear pathogenic effects observed on muscular growth and voluntary feed intake were similar between lines. In contrast, a line difference in body fat was supported both by dorsal and volumetric CT measurements. Specifically, lower fat in the R line compared with the S line was observed equally in infected and uninfected groups, thus providing evidence for a constitutive cost of host resistance. Although this cost is not necessarily disadvantageous in nutrient-rich environments exposing animals to excess fat deposition, its consequences in nutrient-scarce environments may be important to promote sustainable breeding strategies for host resistance.

Effect of thymol on the efficiency of feed utilization and compensatory growth in severe feed-restricted lambs.

The present study aimed to evaluate the effect of thymol on growth performance and apparent total tract digestibility of nutrients in severely feed-restricted lambs. Twenty-one male Baluchi lambs were randomly blocked by live weight into three groups: control without feed restriction (CON), feed restricted (FR), and feed restricted plus thymol (FR + T). The lambs underwent a four-week feed restriction period followed by four weeks of realimentation. Thymol was administered daily to the FR + T group during the feed restriction period. Average daily gain (ADG), average daily feed intake, feed efficiency (FE), partial efficiency of maintenance (PEM), and residual feed intake (RFI) were measured as growth performance parameters. Results showed that the severe feed restriction had adverse effects on ADG and FE, but improved PEM (P < 0.05). The effects of thymol administration on ADG, FE, PEM, and apparent total tract digestibility were not significant (P > 0.05). However, the lambs that received thymol during the feed restriction period showed a negative RFI during realimentation (P < 0.05). Overall, these findings suggest that feed restriction as well as thymol may have the potential to improve efficiency of feed utilization in growing lambs. However, this positive effect is independent of the improvement in nutrient digestibility.

The Post-weaning Growth of Lambs from Crossbreeding Between Garut Ewes with Dorper Rams

This study investigates the performance of post-weaning growth of Garut lambs and the results of crossing Garut ewes with Dorper rams. This research phase occurred in the post-weaning phase period of 3–7 months using 168 lambs consisting of 85 Garut lambs and 83 crossed Dorper lambs in the post-weaning phase with an average body weight of 15.15±3.23 kg. The lambs were assigned to a factorial completely randomized design (2 x 2 factorial experiment). They were then divided into two groups based on breed (Garut and Crossed Dorper) and two sex groups (male and female). Data observed included feed consumption, as fed feed consumption, dry matter (DM) consumption, DM consumption per body weight, crude protein (CP) consumption, total digestible nutrient (TDN) consumption, average daily gain (ADG), and feed conversion. Results showed that consumption of as fed, DM, CP, TDN, and ADG were higher (&lt;i&gt;P&lt;/i&gt;&lt;0.05) in crossed Dorper lambs than in Garut lambs; a total ADG of crossed Dorper, Garut, male, and female lambs were 106.92±11.68, 79.25±10.02, 102.49±17.54, and 86.79±14.48 g/day, respectively. Male lambs showed higher results (&lt;i&gt;P&lt;/i&gt;&lt;0.05) in as-fed feed consumption, DM, DM consumption per body weight, CP, TDN, and ADG than female lambs. The feed conversion of crossed Dorper lamb and male lamb was lower (P&lt;0.05) than that of Garut and female lamb. There was an interaction between male breed and sex at seven months ADG and feed conversion at 4 and 7 months. Sheep from Garut ewes crossed with Dorper rams improved the growth performance of their offspring.

Effects of an essential oil blend rich in cinnamaldehyde and carvacrol on rumen biohydrogenation and fatty acid profile in the longissimus lumborum of growing lambs.

Essential oils extracted from cinnamon bark and oregano are rich in cinnamaldehyde and carvacrol and show potential for promoting animal performance. However, their impact on rumen biohydrogenation and the fatty acid composition of meat has not been reported. The hypothesis of this study was that a blend of essential oils rich in cinnamaldehyde and carvacrol would inhibit rumen biohydrogenation and promote the accumulation of polyunsaturated fatty acids (PUFAs) in lamb meat. The present study evaluated the effect of a blend essential oil (EO) rich in cinnamaldehyde and carvacrol on the nutrient digestibility, rumen biohydrogenation, growth performance, and fatty acid profile of the longissimus lumborum of lambs. Sixty male lambs with an average age of 84 ± 0.98 days and initial body mass of 25.4 ± 0.29 kg (mean ± standard deviation) were assigned randomly to four diets, and supplemented with 0 (EO0), 30 (EO30), 60 (EO60), and 120 (EO120) mg kg-1 dry matter of EO for 60 days. Although dry matter and neutral detergent fiber digestibility all showed a linear decrease (P ≤ 0.02) with increasing quantities of EO, final body mass and average daily gain increased linearly (P = 0.04), and average daily weight gain (ADG)/dry matter intake (DMI) tended to increase linearly (P = 0.07). Increasing EO supplementation resulted in a linear decrease in total volatile fatty acid concentration, acetate molar percentage, and acetate-to-propionate ratio (P ≤ 0.03), with the EO120 treatment being lower than the other EO treatments (P ≤ 0.05). Seven lambs from the EO120 treatment and seven lambs from the EO0 treatment were randomly slaughtered. It was observed that the proportions of C18:2n6c and PUFA in longissimus lumborum were higher in the EO120 treatment than the EO0 treatment (P ≤ 0.05). The relative abundance of Firmicutes in the rumen was decreased by the EO120 treatment in comparison with the EO0 treatment (P ≤ 0.05). Furthermore, the predicted relative abundances of genes encoding for conjugated linoleic acid reductase tended to decrease with the EO120 treatment (P = 0.06). We demonstrated that supplementation of the EO blend rich in cinnamaldehyde and carvacrol can enhance lamb growth performance and promote the deposition of desirable PUFAs in meat. © 2024 Society of Chemical Industry.

Welfare evaluation of fat-rumped lambs under stall feeding condition with different feeder design

Animal welfare is directly related to animal performance and farm profit. It is associated with their autonomy to take feed and water along with a lack of discomfort. Feeding welfare determines farm profit as major cost of a farm is associated with feed. The objective of the study was to investigate the effect of feeder design on lamb welfare evaluated through feeding behaviour and lamb performance. Sixteen growing fat-rumped lambs of 3-4 months of age were categorized into two groups with an average weight of 23.20±0.25 kg. Group I lambs were fed in conventional feeder, i.e. without divider and group II in designed feeder, i.e. with divider, respectively. The eating time was significantly low in group I with longer and strong agonistic behaviour suggesting intense competition within the group. This group showed minimal weight gain and maximal feed wastage due to extreme struggle for food during the period of the study. The time spent in comfort behaviours like lying rumination was more and agonistic behaviour was less in group II lambs. They showed significantly higher bodyweight gain. It can be concluded from the study that group feeding of growing lambs in feeder with divider allocates designated space for individual lamb, reduces agonistic behaviour and brings better growth in lambs under stall feeding conditions.

A Dynamic Tool to Describe Lamb Growth and Its Use as a Decision Support System.

A dynamic model has been developed to simulate aspects of feedlot lamb growth and body composition, including energy and protein requirements, growth rate, composition of gain, and body mass. Model inputs include initial body mass (kg), standard final mass (kg), age (days), and dietary energy concentration (Mcal·kg-1). The model was assessed as a decision support tool using a dataset of 564 individual measures of final body mass and diet energy. The simulations provide graphical and numerical descriptions of nutrient requirements, composition of gain, and estimates of animal performance over time. The model is accurate and precise, with a root mean squared error of 7.79% of the observed final body mass and a coefficient of determination of 0.89 when simulating the same variable. The model can be used as a reliable decision support tool to estimate final body mass and the days on feed required to reach a certain final mass with precision and accuracy. Moreover, the dynamic model can also serve as a learning tool to illustrate practical principles of animal nutrition, nutrient requirement relationships, and body composition changes. This model holds the potential to enhance livestock management practices and assist producers in making informed decisions about feedlot lamb production.

Supplementation of coated sodium butyrate relieved weaning stress and reshaped microbial flora in weaned lambs.

Weaning is an important period in the growth and development of lambs. Thus, effectively reducing the occurrence of weaning stress is critical for maintaining lamb production. Coated sodium butyrate has been shown to reduce inflammation, promote intestinal health, and maintain homeostasis. However, the application and potential mechanism of coated sodium butyrate in alleviating weaning stress in lambs are still unclear. To evaluate the effects of coated sodium butyrate on the growth performance, antioxidant capacity, and gut microbiota of weaned lambs, 10 weaned lambs of 21-day-old were randomly divided into two groups: the CON group (basal diet) and the NaB group (basal diet +3 g/kg of coated sodium butyrate). The trial lasted 21 days. The experimental results showed that compared to the CON group, coated sodium butyrate supplementation in the diet significantly increased the average daily weight gain and daily feed intake of lambs (p < 0.05). In addition, compared to the CON group, the addition of coated sodium butyrate also significantly decreased the serum MDA level of lambs (p < 0.05). Notably, the addition of coated sodium butyrate did not have a significant effect on the cecal microbiota, while increasing the diversity of colonic microbiota and promoting the abundance of Lachnospiraceae, Verrucomicrobiota, Akkermansia, Roseburia, and Sinobacteraceae, which are associated with the nutrient absorption of lambs (p < 0.05). These results indicate that dietary supplementation with coated sodium butyrate could promote the growth and antioxidant capacity of weaned lambs and alleviate weaning stress.

Impacts of a highly pathogenic ovine Eimeria ovinoidalis on the growth of Hu lambs

The apicomplexan Eimeria ovinoidalis is distributed worldwide. It can cause clinical coccidiosis, which is one of the most pathogenic species in sheep, reducing growth rates and resulting in significant economic losses in the industry. Its principal clinical sign is profuse diarrhoea in young animals. In this study, we established a model of E. ovinoidalis infection in lambs to understand its pathogenicity and evaluate the gut microbiota and fecal metabolite profiles. Specifically, we observed a significant shift in the abundance of bacteria and disrupted metabolism in lambs. Especially during the peak period of excrete oocysts, it promoted the reproduction of some harmful bacteria in Proteobacteria and Actinobacteriota, and reduced the abundance of beneficial bacteria such as Lachnospiraceae and Rikenellaceae. In the later stage of the patent period, the abundance of harmful bacteria in the intestine decreased, the abundance of beneficial bacteria which could produce anti-inflammatory substances began to increase, and the abundance and diversity of intestinal flora also tended to parallel with the control group. Coccidia infection could lead to the increase of differential metabolites and metabolic pathways between infected and control group, but the difference decreased with time. During the peak period of excrete oocysts, although the antimicrobial metabolites such as Lividamine were up-regulated, the excess of these metabolites could still induce the production of endotoxin, while Butanoic acid and other anti-inflammatory metabolites decreased significantly. A metabolomics analysis showed that E. ovinoidalis infection altered metabolites and metabolic pathways, with biosynthesis of unsaturated fatty acids, Teichoic acid biosynthesis and Butanoate metabolism as the major disrupted metabolic pathways. Details of the gut microbiota and the metabolome after infection with E. ovinoidalis may aid in the discovery of specific diagnostic markers and help us understand the changes in parasite metabolic pathways.

The Impact of Folic Acid and B12 Administration on Growth, Wool Traits and Some Hormones Concentrations of Male Arabi Lambs

This study aimed to investigate the effects of folic acid and vitamin B12 administration on the growth and wool traits in male lambs. A total of fifteen animals was used from 1st February 2015 to 30th April 2015, divided into three treatment groups. The first group served as a control, the second group received a folic acid dosage equivalent to 0.5 mg per kilogram of body weight per head, and the third group received a vitamin B12 dosage equivalent to 0.1 mg per kilogram of body weight per head. The vitamins were administered orally twice a week. The results showed a significant improvement (P&lt;0.05) in final body weight, daily gain, and total weight gain in the vitamin B12 and folic acid groups compared to the control group. Additionally, there was a significant (P&lt;0.05) increase in all wool characteristics, except for crimp number, in the folic acid group compared to the control group. The study demonstrated significant relationships between body weight and every aspect of wool quality except for fiber length. There was a significant (P&lt;0.05) increase in the concentrations of growth and thyroxine hormones in the vitamin B12 and folic acid groups compared to the control group, particularly in the second and third months of the experiment. No significant difference in insulin hormone concentration among the groups was observed during the 90-day experiment. In conclusion, administering vitamin B12 and folic acid are orally administered twice a week to improve growth, increase hormone concentrations (thyroxine and growth hormone), and improve wool quality

ВЛИЯНИЕ МОЛОЧНОСТИ И ДОЕНИЯ МАТОК НА РОСТ И ПРОДУКТИВНОСТЬ ЯГНЯТ

A shortening of the milking period has a negative effect on lambs, and this effect is more pronounced the earlier the beating is carried out and milking begins, but the growth of young animals is highly dependent on the level of non-dairy nutrition and rearing technology. In this regard, the study of the influence of milking on the quality and productivity of the offspring was carried out taking into account the characteristics of feeding and keeping lambs. The experiment was carried out in 2023 in the foothill zone of the Republic of North Ossetia-Alania on sheep of the Tushino breed. All experimental lambs were divided into two groups: a control group, raised in the usual manner, and an experimental group, whose queens were not milked. All lambs had coarse wool, were kept in the same conditions and were allowed access to the uterus 2 times a day - in the morning and in the evening, but the rest of the time they were kept separately. Milking of sheep on the farm began in early June, that is, when the lambs reached 2.5 months of age. Lambs of both groups were completely weaned at 5 months of age. It was found that the lambs of the experimental group, whose uterus were not milked, grew better and had a greater body weight at the time of lambing than the control group. The difference in body weight was 1.92 kg for rams and 2.42 kg for lambs, in favor of the experimental group. After the start of milking of the queens of the control group, the picture changes. During the third month of life, the absolute increase in the experimental group was 6.07-5.34 kg (little lambs), and in the control group - 4.56-3.69 kg. The lambs spent the fourth month of life on alpine pastures, where the growth of the control group (6.47-5.62 kg) was lower than that of the experimental group (5.87-5.39 kg). The last month of the suckling period is characterized by a significant drop in the growth of lambs in the control group (3.16-2.88). The growth of lambs in the experimental group also decreased (4.83-4.67).

Fertility and Some Growth Characteristics of Lambs in Akkaraman Sheep Grown in Çorum Province

Objective: The aim of this study was to determine the reproductive efficiency and lamb growth characteristics of Akkaraman sheep in Çorum province under breeder conditions. Material and Methods: The animal material of the study consisted of 2214 Akkaraman sheep and 2508 Akkaraman lambs from three different farms located in the center of Çorum province. The study was conducted between 2019 and 2022. In the study, reproductive characteristics of Akkaraman sheep and birth, weaning live weights, and survival of lambs were determined. Results: The mean birth weight of lambs was 4.15 kg, and the mean weaning weight (75th day) was 19.58 kg. Birth and weaning weights differed according to year, farm, type of birth, and sex (P

Effects of probiotic-supplemented milk replacer on growth, blood biochemistry, fermentation, digestibility, and carcass traits in lambs

The objective of this study was to investigate the effects of feeding cow's milk replacer and probiotic supplementation on growth performance, blood metabolites, ruminal fermentation parameters, and nutrient digestibility in male lambs, with ewe's milk serving as the control treatment. Eighteen male lambs with an average initial body weight of 5.0 ± 1.2 kg and age of 15 ± 4 days were randomly assigned to three experimental groups: ewe's milk, cow's milk replacer, and cow's milk replacer with probiotic supplementation. The experiment was conducted using a completely randomized design. Lambs fed ewe's milk showed significantly higher average daily gain (218.4 g/day) compared to those fed cow's milk replacer (183.7 g/day) or cow's milk replacer with probiotic (209.1 g/day). Similarly, dry matter intake was highest in the ewe's milk group (585.6 g/day) compared to the cow's milk replacer (435.9 g/day) and cow's milk replacer with probiotic (510.5 g/day) groups. Blood glucose levels were higher in the ewe's milk group (75.3 mg/dL) compared to the cow's milk replacer (70.3 mg/dL) and cow's milk replacer with probiotic (72.1 mg/dL) groups. Probiotic supplementation resulted in increased blood urea nitrogen (15.6 mg/dL) and total protein (7.3 g/dL) levels compared to the other groups. Furthermore, the ewe's milk group showed higher apparent dry matter (76.1%) and crude protein (68.5%) digestibility compared to the other treatments. The fecal score on day 30 was higher in the cow's milk replacer group (2.34) compared to the ewe's milk (1.24) and cow's milk replacer with probiotic (1.45) groups. There were no significant differences in the carcass traits of the experimental lambs. In conclusion, based on the results of this study, it seems that feeding cow's milk + probiotic as a replacement for ewe's milk did not significantly affect the performance, carcass traits, and blood and fermentation parameters in infant lambs.