Lamb Growth Research Articles

Mating Season Influences Placental Characteristics, Plasma IGF Concentration, and mRNA Expression without Affecting Lamb Birth Weight in Akkaraman Ewes

Seasonal variations significantly impact lambs’ birth weight and post-natal growth of lambs, yet the underlying physiological mechanisms remain insufficiently explored. Therefore, this study examined the effects of mating season on lamb birth weight, placental characteristics, maternal concentrations of insulin-like growth factors (IGFs) in plasma, and placental mRNA expression levels of IGFs in Akkaraman ewes reared under extensive conditions. Ewes were mated in the breeding season (September; n = 35) and out-of-breeding season (April; n = 27). Blood samples were taken from the jugular vein of all ewes using a vacutainer in sterile heparin tubes every month from mating to parturition. Post-lambing, both dam and lamb weights were recorded, and placental characteristics were documented within 12 hours of parturition in both seasons. The number and weight of cotyledons were higher (P<0.05) in ewes mated during the breeding season than those mated during the out-of-breeding season. Also, ewes mated during the breeding season demonstrated thicker large cotyledons (P<0.05). Although placental and cotyledonal efficiencies were similar in both mating seasons, volumetric cotyledon efficiency was higher (P<0.05) in ewes mated during the out-of-breeding season than in those bred during the breeding season. Additionally, ewes mated in the breeding season exhibited higher plasma concentration of IGF-I at three months of gestation than ewes mated in the out-of-breeding season (123.8 ± 9.8 vs. 99.3 ± 11.4 ng/ml, respectively; P<0.05). Although the mating season did not affect the IGF-I gene’s placental mRNA expression levels, the IGF-II gene’s expression level was notably higher (P<0.05; fold change: 2.84) in ewes mated during the breeding season. The results suggest that mating season influences placental characteristics, maternal plasma IGF-I concentrations, and IGF-II gene expression levels of cotyledons due to alterations in cotyledon numbers and size on the surface of the placenta.

The Effects of Housing on Growth, Immune Function and Antioxidant Status of Young Female Lambs in Cold Conditions

Cold conditions in northern China during winter may reduce sheep growth and affect their health, especially if they are young, unless housing is provided. We allocated 45 two-month-old female lambs to be housed in an enclosed building, a polytunnel, or kept outdoors, for 28 days. The daily weight gain and scalp and ear skin temperature of outdoor lambs were less than those of lambs that were housed in either a house or polytunnel; however, rectal temperature was unaffected by treatment. There was a progressive change in blood composition over time, and by the end of the experiment, outdoor lambs had reduced total antioxidant capacity (T-AOC), catalase (CAT), glutathione peroxidase (GSH-Px) and total superoxide dismutase (T-SOD) and increased malondialdehyde compared to those in the house or polytunnel. In relation to immune responses in the lambs’ serum, in the polytunnel, immunoglobulin A (IgA), tumor necrosis factor-α (TNF-α) and interleukin-4 (IL-4) were higher and immunoglobulin G (IgG) lower compared with the concentrations in lambs that were outdoors. Over the course of the experiment, genes expressing heat shock proteins and antioxidant enzymes increased in lambs in the outdoor treatment, whereas they decreased in lambs in the indoor treatments. It is concluded that although there were no treatment effects on core body temperature, the trends for progressive changes in blood composition and gene expression indicate that the outdoor lambs were not physiologically stable; hence, they should not be kept outdoors in these environmental conditions for long periods.

The effect of climate index on growth values from birth to breeding in Akkaraman sheep.

Under specific agroclimatic conditions, growth is an adaptability parameter resulting in reduced performance with decreasing animal comfort of a sheep breed. In this study, a total of 1011 lambs' live weights (LW) and average daily weight gains (ADG) in 16 different farms between 2018 and 2020 (birth to 18 months) were determined in Akkaraman herds raised in Çankırı Province of Turkey. Comprehensive Climate Index (CCI) was examined to determine the effect of climate. Thermal comfort limits in CCI values were classified as CCI-1.cold (≤ 5 ℃), CCI-2.comfort (5-25 ℃), and CCI-3.warm (≥ 25 ℃). The climatic values that all lambs examined were exposed to according to index value groups in periods from birth to 18 months of age were prepared daily. The lambs were exposed to comfort environment in the majority of the days in the MP0-3 (77.7%) and MP12-18 (50.1%) periods. The lambs mostly in the MP3-6 period (72.2%) were above the warm stress threshold, but in the MP6-12 period, 54.7% were above the cold stress threshold. Overall mean LW of lambs at birth, at 3, 6, 12, and 18 months were 4.29 kg, 35.1 kg, 39.1 kg, 45.4 kg, and 52.6 kg, while the ADG values between birth-3 months, 3-6 months, 6-12 months, and 12-18 months were 341.8 g, 54.5 g, 42.9 g, and 56.8 g respectively. Periodically, CCI values were realized as 10-15, 25-30, and 18-22 in the growth periods of 0-3, 3-6, and 12-18 months, respectively, and ADG values of the lambs were found to be similar within their own periods. However, when the CCI values of the lambs increase to 5 and above in the 06-12-month period, there is a decrease in their live weight. As a result, climatic index values did not have a negative effect on the growth and development values of lambs in cold conditions in general, but warm conditions affected the animals negatively.

Effects of Tail Vegetable Fermented Feed on the Growth and Rumen Microbiota of Lambs.

This study explored the impact of integrating fermented feed into the starter diet of lambs, focusing on growth, health, serum antioxidants, immune markers, rumen fermentation, and microbial communities. Thirty-six ten-day-old female Tail Han lambs were randomly divided into three experimental groups, which were separately fed with alfalfa hay (LA group), tail vegetable fermented feed (LB group), and tail vegetable fermented feed supplemented with 0.1% microbial inoculants (LC group) during the experimental period. This study assessed the influence of fermented feed on various parameters, including growth performance, fiber degradation, rumen fermentation, enzymatic activities, and ruminal histomorphology. The results indicate that compared to the control group, the addition of fermented feed can increase the daily weight gain of lambs. Simultaneously, the addition of fermented feed can enhance the total antioxidant capacity of serum (p < 0.05). The addition of fermented feed promoted the increased height of villi in the duodenum or jejunum of lambs (p < 0.05), and the ratio of villi height to crypt depth in the LB and LC groups was also improved (p < 0.05). The addition of fermented feed increased the richness and diversity of the rumen microbial community in lambs (p < 0.05), primarily increasing the relative abundance of Ruminococcus_1, Ruminococcaceae_UCG-005, Lachnospiraceae, and Lachnospiraceae_NK4A136_group.

Preparation and activity study of Ruoqiang jujube polysaccharide copper chelate.

Background: Polysaccharide metal chelate exhibit both immunoregulatory activity and metal element supplementation effects. Methods: In this study, Ruoqiang jujube polysaccharide copper chelate (RJP-Cu) was prepared and the preparation conditions were optimized using the response surface method. Subsequently, RJP-Cu was administered to lambs to evaluate its impact on growth performance, copper ion (Cu2+) supplementation, immune enhancement, and intestinal flora was evaluated. Results: The results indicated that optimal RJP-Cu chelation conditions included a sodium citrate content of 0.5 g, a reaction temperature of 50°C, and a solution pH of 8.0, resulting in a Cu2+ concentration of 583°mg/kg in RJP-Cu. Scanning electron microscopy (SEM) revealed significant structural changes in RJP before and after chelation. RJP-Cu displaying characteristic peaks of both polysaccharides and Cu2+ chelates. Blood routine indexes showed no significant differences among the RJP-Cu-High dose group (RJP-Cu-H), RJP-Cu-Medium dose group (RJP-Cu-M), RJP-Cu-low dose group (RJP-Cu-L) and the control group (p > 0.05). However, compared with the control group, the RJP-Cu-H, M, and L dose groups significantly enhanced lamb production performance (p < 0.05). Furthermore, RJP-Cu-H, M, and L dose groups significantly increased serum Cu2+ concentration, total antioxidant capacity (T-AOC), catalase (CAT), and total superoxide dismutase (T-SOD) contents compared with control group (p < 0.05). The RJP-Cu-H group exhibited significant increases in serum IgA and IgG antibodies, as well as the secretion of cytokines IL-2, IL-4, and TNF-α compared to the control group (p < 0.05). Furthermore, RJP-Cu-H group increased the species abundance of lamb intestinal microbiota, abundance and quantity of beneficial bacteria, and decrease the abundance and quantity of harmful bacteria. The RJP-Cu-H led to the promotion of the synthesis of various Short Chain Fatty Acids (SCFAs), improvements in atrazine degradation and clavulanic acid biosynthesis in lambs, while reducing cell apoptosis and lipopolysaccharide biosynthesis. Conclusion: Thus, these findings demonstrate that RJP-Cu, as a metal chelate, could effectively promote lamb growth performance, increase Cu2+ content, and potentially induce positive immunomodulatory effects by regulating antioxidant enzymes, antibodies, cytokines, intestinal flora, and related metabolic pathways.

Artificially reared ewes cannot be distinguished from natural reared ewes based on observed maternal behavior or lamb weaning weights.

Artificially rearing lambs is an important component of United States sheep production as some flocks select for increasing litter size to boost productivity. However, there is a conception among shepherds that artificially reared ewe lambs will ultimately result in poor mothers since they were not naturally raised. The objective of this study was to determine if differences in maternal behavior could be detected between ewes raised artificially and those raised naturally and if dam rearing type had an impact on lamb growth performance. Forty-eight ewes were enrolled comprised of 4 equal sized groups: artificially reared primiparous, naturally reared primiparous, artificially reared multi-parous, and naturally reared multi-parous. Ewes were observed using remote cameras to record maternal behaviors toward the lambs during and shortly after parturition. Behavior of 29 ewes during the first hour after parturition was analyzed. Independent multivariable regression models were evaluated for: proportion of time spent grooming, proportion of time spent helping the lambs nurse, number of helpful bouts, and the number of negative bouts. No statistically significant difference (P < 0.05) was detected between artificially reared and naturally reared ewes for the proportion of time spent grooming and the proportion of time spent helping the lambs nurse. Historical flock data were utilized to evaluate lamb growth between artificially and naturally reared ewes. No detrimental associations between artificially reared ewes and lamb weaning weights were observed. This study shows that artificially reared ewes are no different in terms of mothering behaviors and may be used as potential replacement candidates.

Negative dietary cation and anion difference supplementation of twin-bearing Merino ewes grazing pasture in late gestation did not affect lamb growth or survival.

Each year in Australia, 53% of lamb mortalities are attributed to dystocia, with subclinical maternal calcium deficiencies likely contributing to dystocia rates. A negative dietary cation and anion difference (DCAD) diet has increased circulating calcium in sheep. Therefore, this study aimed to investigate the effects of supplementing twin-bearing, grazing ewes with a negative DCAD partial mixed ration (PMR) during late gestation on ewe calcium and magnesium concentrations and subsequent lamb growth and survival. On day 120 of gestation (dG), blood samples were collected from 115 twin-bearing Merino ewes and analyzed for glucose, ketone bodies, pH, ionized calcium, and serum calcium and magnesium. On dG 130, ewes were moved into lambing paddocks and placed in the following 2 treatment groups; ewes receiving a positive DCAD PMR (DCAD = 287 mEq/kg DM; n = 58) and ewes receiving a negative DCAD PMR (DCAD = -125 mEq/kg DM; n = 57) fed as a PMR. On dG 140, a blood and urine sample were collected. The urine was tested for pH. Pasture samples were taken on dG 133 and 149 and tested for DCAD and mineral content. When a lamb was 6 to 18h old, survival, vigor score, liveweight (LW), rectal temperature, blood glucose, and body morphology were recorded. At 10 d of age, lamb LW and survival were recorded and a milk sample was collected from ewes. At 44 d of age, lamb LW and survival were recorded. The DCAD of the pastures across the 6 paddocks ranged from 598 to 893 mEq/kg DM. There were no differences in lamb survival, weight, or viability at any timepoint (P > 0.05). There were no differences in mineral status, metabolic state, or acid-base balance between the positive and negative DCAD-supplemented ewes (P > 0.05) during supplementation (dG 140). Supplementing a negative DCAD diet to ewes grazing pasture during late gestation did not improve lamb survival. The blood and urine pH of the negative DCAD-supplemented ewes indicated a mild metabolic acidosis was not reached due to the high DCAD of the pastures. Further research needs to take careful consideration of the DCAD of pasture when designing a negative DCAD supplement in order for it to be effective.

The effect of repeated lipopolysaccharide endotoxin challenge on immune response of breeding ewes and subsequent lamb performance.

Infectious disease caused by exposure to Gram-negative bacterial endotoxin lipopolysaccharide (LPS) is recognized to suppress female fertility. However, the effect of varying low-dose endotoxin exposure during distinct stages of follicle development on immune response, reproductive performance, and lamb performance has yet to be elucidated. Therefore, the objective of this study was to evaluate acute phase response, mRNA abundance of inflammatory markers, reproductive performance and lamb growth characteristics of ewes challenged with subclinical doses of LPS. Rambouillet ewes (n = 36; 68.2±1.1kg; age 3 to 7 yr) stratified by body weight (BW) and age were assigned to treatment groups. Ewes received subcutaneous injections of saline (CON, n = 12), 1.5 µg/kg BW LPS (LOW, n = 12), or 3.0 µg/kg BW LPS (HIGH, n = 12) on days 5, 10, and 15 of a synchronized follicular wave. Ewes were subsequently placed with a raddle-painted ram on day 16 for a 35-d breeding season. On treatment days 5 and 15, blood samples, peripheral blood leukocytes, and rectal temperature were collected before and at regular intervals for 12h after LPS challenge. Immune response to LPS was confirmed by increased temperature and serum cortisol concentrations on days 5 and 15. Endotoxin increased circulating plasma concentration of the acute phase protein, haptoglobin by greater than 15%, in both LPS-treated groups on days 5 and 15 at 12h compared with control (P≤ 0.05). Pro- and anti-inflammatory mRNA gene expression demonstrated no differences in expression for tumor necrosis factor-α or peroxisome proliferator-activated receptor gamma among treatment groups (P > 0.10). Likewise, Toll-like receptor 4 (TLR4), interleukin-8 (IL-8), and superoxide dismutase 2 (SOD2) expression was similar among treatment groups on day 5. However, ewes challenged with LPS on day 15 displayed greater mRNA expression for TLR4 from 2 to 6h (P < 0.05), a 7-fold increase for IL-8 from 1.5 to 2.5h (P < 0.05), and 8-fold induction for SOD2 from 2 to 6h (P < 0.05) as compared with controls. First service conception rates were 90% for control ewes and 75% for both treated groups (P = 0.84). Treated ewes demonstrated a reduction in lamb birth weight compared with controls (P ≤ 0.05) and a tendency for reduction of 60-d adjusted weaning weight (P = 0.09). Data suggest that subacute endotoxin exposure aligning with key follicle and oocyte maturation events results in detrimental growth performance of the subsequent lamb.

Estimating body composition using CT scans of cross-bred lambs fed at 2feeding levels and 2stages of maturity to inform predictive growth models.

Livestock producers would benefit from more precise predictions of the growth response from nutrients consumed. Previously published models are often limited by the realities of data collection and are unable to account for alterations to body composition, due in part to the response of visceral organs to an alternate diet. The computerized tomography (CT) scanning of lambs enables the analysis of changes in body composition of individual animals over time, potentially supporting better model development and testing. The aim of this experiment was to develop a repeatable method for the analysis of live lamb body composition using CT scans. A secondary aim was to compare the data collected from CT scanning during a feeding trial to 2 predictive lamb growth models. Cross-bred lambs were fed 2 feeding levels at 2 stages of maturity, with CT scans at the beginning and end of each 8-wk feeding period. The CT scan-derived values for body composition taken at the beginning of feeding periods were used as inputs for 2 existing lamb growth models. Predictions of body composition were compared with CT scan-derived values at the end of feeding periods. The CT scan analysis method used a proportion of images from each lamb to reduce manual image editing. The method was developed by comparing the estimated mass and volume of empty body components using all available CT scans to estimated values using a reduced number of scans from 12 lambs. The CT scan-derived lean tissue mass aligned with model predictions at the end of each feeding period, however, CT scan-derived fat mass was greater than predictions by both models especially for the high feeding level at the later stage of maturity. These results highlight that the analysis of body composition using CT scans requires further validation, particularly for the viscera, and that models likely require refinement to better predict the efficiency of energy utilization by different tissues. The use of live animal CT scans can provide more accurate predictions of the growth of saleable products than measuring liveweight alone and will enable ruminant growth models to better adapt to different genetics and changing diets than comparative slaughter. To replicate the current data using comparative slaughter would require 4 times the animals, as individual lambs were CT scanned 4 times in this study, demonstrating the potential value of CT scanning in live animal research.

Human social enrichment is linked with reduced mortality in artificially reared ewe lambs.

Growth of lambs in an artificial rearing system is key to the economic success of sheep-milking farms. Social enrichment in the form of quiet human contact has been shown to increase growth rates of lambs after weaning, perhaps by reducing stress and enhancing immune function. One hundred fourteen artificially reared dairy ewe lambs were assigned either to a Social condition receiving quiet human company in three 20-min segments per day, or a Control condition without quiet human contact. Feeding and housing conditions were otherwise identical. Starting weights for the Social (M = 6.29kg; SD = 1.19 kg) and Control (M = 6.38kg; SD = 0.93 kg) lambs were the same, as were their weights after 3 weeks (Mcontrol = 8.89 kg, SD = 2.55 kg, Msocial = 8.63 kg, SD = 2.16 kg). Mortality rates were significantly lower (p =0.041) in the Social condition (0%) than Control (8%). Thus, social enrichment may be important for the wellbeing of lambs and for economic viability in lamb-rearing.

Managing weaning issues in lambs and ewes

Background: Weaning has long been considered a stressful time for both lambs and ewes and, as such, many problems can be encountered during this time. The timing of weaning is generally when lambs reach ages of between 12 and 14 weeks; however, rather than being a fixed time event this should be based on the grazing available, ewe body condition score and lamb growth rates.Aim of the article: This article discusses common issues encountered by both ewes and lambs at weaning time and outlines how to minimise these problems.

Effect of concentrate feed containing guava waste meal on growth and haemato-biochemical profile of ram lambs

Effect of concentrate feed containing guava waste meal on growth and haemato-biochemical profile of ram lambs

Линейный рост молодняка романовской породы и ее помесей с эдильбаевской

The article presents the results of studying the linear growth of lambs and gelded lambs of the Romanov breed (group I), its first generation crossbreeds with Edilbai - ½ Romanov × ½ Edilbai (group II) and the second generation ¼ Romanov × ¾ Edilbai (group III). It was found that due to the manifestation of the crossing effect, the crossbreed gelded lambs of groups II and III exceeded in size all measurements of the body articles of purebred peers of group I. At the same time, the circumference of the chest behind the shoulder blades, the oblique length of the trunk, the width and depth of the chest were characterized by the highest intensity of height measurements, as well as the circumference of the pastern increased less intensively with age.

Enhancing lamb growth and meat quality: analysis of kazakh fat-tailed and crossbred in central Kazakhstan's sharply continental climate.

The article presents the results of scientific research on the production of lamb in the conditions of the Akmola region. The experiment was conducted on purebred Kazakh short-tailed rough-haired and cross-bred sheep obtained from industrial crossing of Kazakh short-tailed rough-haired queens with sheep- producers of the hampshire breed. Further, the article presents the results of feeding and fattening, as well as the morphological composition of the carcass of sheep of the Kazakh coarse-haired sheep breed of different ages. The object of the study for feeding and fattening were three groups of experimental sheep of the above-mentioned breed, where compound feed was included in the diet of the I experimental group in the form of top dressing, in the II experimental group, grain waste was also used for top dressing, and the control group was kept in the feed without top dressing. Based on the study of the feeding of experimental sheep, it was found that the absolute increase during the feeding period in experimental sheep who received fertilization in the form of compound feed is higher than in their peers, respectively, by 0.2 and 1.49 kg. In terms of morphological and varietal composition, in particular, the number of cuts of grade 1, there was also an advantage of experimental sheep that received fertilization in the form of compound feed compared to their peers, respectively, by 2.3-8.3%. In general, the results of a study on the growth, development and slaughter qualities of experimental sheep, i.e. purebred Kazakh short-tailed rough-haired and crossbred, obtained from crossing with sheep producers of the precocious breed "hampshire" showed that from the moment of birth to 2 and 4 months. For example, crossbred sheep were slightly superior to purebred peers in terms of the studied indicators. In particular, the results of feeding sheep of the Kazakh coarse-haired broad-tailed breed from 4 to 6 months, depending on the top dressing.

Exploring the metabolomic landscape: Perilla frutescens as a promising enhancer of production, flavor, and nutrition in Tan lamb meat

Addressing health-related concerns linked to the metabolite profile of lamb meat has become paramount, in line with the growing demand for enhanced flavor and taste. We examined the impact of Perilla frutescens seeds on Tan lamb growth, carcass traits, and metabolite profiles. Three diets were employed: a low-concentrate group (LC), a high-concentrate group (HC), and a PFS group (the LC diet supplemented with 3% Perilla frutescens seeds) on a dry matter basis. Forty-five male Tan-lambs (approximately six months) with similar body weights (25.1 kg ± 1.12 SD) were randomly assigned to one of these three groups for 84-day feeding, including an initial 14-day adjustment phase. The supplementation of PFS resulted in increased average daily gain (P < 0.01) and improved carcass quality and meat color (P < 0.05). Additionally, it led to an enhancement in omega-3 polyunsaturated fatty acids (P < 0.05) and a reduction in the omega-6/omega-3 ratio (P < 0.05). Using gas chromatography–mass spectrometry, 369 volatile compounds were identified with enhanced levels of acetaldehyde and 1,2,4-trimethyl-benzene associated with PFS (P < 0.05). Among the 807 compounds identified by ultra-high performance liquid chromatography-mass spectrometry, there were 66 significantly differential compounds (P < 0.05), including 43 hydrophilic metabolites and 23 lipids. PFS supplementation led to significant alterations in 66 metabolites, with three metabolites including 2,5-diisopropyl-3-methylphenol, 3-hydroxydecanoic acid, and lysophosphatidylcholine (15:0) emerging as potential PFS-related biomarkers. The study indicates that PFS supplementation can enhance Tan-lamb growth, feed efficiency, and meat quality, potentially providing lamb meat with improved flavor and nutritional characteristics.

Effects of maternal calcium propionate supplementation on offspring productivity and meat metabolomic profile in sheep.

This study determined the effect of dietary calcium propionate (CaPr) as a source of energy supplementation during the First Half of Gestation (FMG), the Second Half of Gestation (SMG), and during All Gestation (AG), on offspring post-weaning growth performance, meat quality, and meat metabolomic profile. Thirty-one pregnant ewes were assigned to one of four treatments: a) supplementation of 30 gd-1 of CaPr during the first half of gestation (day 1 to day 75, n = 8) (FMG); b) supplementation of 30 gd-1 of CaPr during the second half of gestation (day 76 to day 150, n = 8) (SMG); c) supplementation of 30 gd-1 of CaPr during all gestation (AG, n = 8); d) no CaPr supplementation (control; CS, n = 7). The ewes were ad libitum fed a basal diet based on oat hay and corn silage. Ewes were distributed in a completely randomized unbalanced design to four treatments. The FMG group had lower (P ≤ 0.05) birth weight and weaning weight than the CS group. However, the average daily gain was similar across all treatments. Empty body weight and FMG had lower values (P ≤ 0.05) than the other groups. Both FMG and AG had lower hot carcass weight (P ≤ 0.05) compared to CS, while CaPr treatments resulted in reduced hot carcass yield (P ≤ 0.05). Meat color and texture were similar among treatments. A principal component analysis between gestation stages showed a trend for separating CS and FMG from SMG and AG, and that was explained by 93.7% of the data variability (PC1 = 87.9% and PC2 = 5.8%). Regarding meat metabolomic profile, 23 compounds were positively correlated between all treatments. Only 2 were negatively correlated (eicosane and naphthalene 1,2,3); but tetradecanoic acid, hexadecane, undecane 5-methyl, (-)-alpha, hexadecenoic acid, octadecanoic acid, and octadecane had a highly significant correlation (P ≤ 0.05). Overall, dam supplementation with CaPr during different periods of gestation provoked changes in meat metabolites related to the biosynthesis of fatty acids in lambs without negative changes in lamb's growth performance and carcass quality.

The effect of increasing extruded linseed level on nutrient digestibility, growth, carcass characteristics, and non-carcass components of lambs from two genotypes.

This research aimed to study the effect of extruded linseed level on digestibility, growth, carcass, and non-carcass components of two genotypes' lambs. For this, 36 lambs, with an average body weight (BW) of 21.3 ± 3.4 for Queue Fine de l'Ouest (QF) and 17.8 ± 2.9kg for the cross QF × D'man (QF × D), were randomly divided into three groups of 12 lambs each (six per genotype) in a 12-week experiment. Sheep in each group received individually oat hay ad libitum and one of three concentrates containing 0% (control), 15% (L15), and 30% (L30) of extruded linseed on a dry matter basis. All concentrates were isocaloric and iso-nitrogenic. In the last 2weeks, digestibility was measured, and then all lambs were slaughtered. The increasing level of extruded linseed did not affect hay and total dry matter (DM) intake as well as nutrient digestibility, except the neutral detergent fiber (NDF) digestibility which was significantly (P < 0.05) reduced by the diet treatment (66.4, 57.8, and 53.0% for C, L15, and L30, respectively). In addition, the different linseed levels resulted in similar average daily gain, final BW, carcass traits, and non-carcass components except the rumen and liver weights which were significantly (P < 0.05) reduced by the increasing linseed level. However, the addition of extruded linseed improved (P < 0.05) the weight of the heart. The carcass tissular composition was not affected by the dietary treatment guarding a similar proportion of muscle, bone, and fat. However, the growth performance and carcass traits were higher for cross QF × D than QF lambs. In addition, the carcasses were leaner (less fat and more muscle) for the cross genotype (P < 0.05) than the pure QF breed. It was concluded that extruded linseed can be used in lamb diet without adverse effects on growth performance and carcass components. Furthermore, the cross could be planned given it resulted in higher growth and better carcass composition.

Growth Performance of Ouled Djellal Male Lambs at Semi-Arid Region of Setif/Algeria

Herd sheep is the leading supplier of red meat in Algeria, which places fattening lambs the animal speculation of choice. Despite the extent of this practice and its importance in the national economy, few studies have been devoted to characterizing it. Precisely, the aim of the present work is to study the growth performance Ouled Djellal lambs male in the fattening phase at semi-arid region of Serif. A set of 43 weaned lambs aged 7 months and over are monitored and weighed regularly every ten days for two months. The animals are fed with a commercial concentrate, wheat straw and water ad-libitum. The results obtained on the male lambs growth remain acceptable. Thus, the initial average live weight is 33±1.48 kg and the final average live weight is 43±1.44 kg, which gives us an average daily gain (ADG) of 165±45 g/d. This reveals the growth potential of Ouled Djellal lambs and its preferred choice by breeders-fatteners. While remembering that the majority of lambs were grass-fed before fattening period. There is therefore poor exploitation growth potential of these lambs, food deficits and poor management breeding are probably the cause.

378 Genetic Parameter Estimates of Post-Weaning Growth and Gastrointestinal Nematode Infection Traits of Katahdin Lambs

Abstract The objective of this study was to estimate heritability of, and genetic correlations between lamb growth and gastrointestinal nematode (GIN) infection. Lambs were weighed and weaned at ~60 days of age and body weight (BW), fecal egg count (FEC), FAMACHA score (FAM) and packed cell volume (PCV) were recorded at ~90, 120, and 150 d of age. Lambs were not dewormed and FEC was transformed as: LFEC = log10(FEC+25). Average daily gain (ADG) was calculated from weaning to 90 days of age (ADG90) as well as 90 to 120 (ADG120) and 120 to 150 days (ADG150). Each trait (ADG, LFEC, PCV and FAM) was analyzed separately within each timepoint. The number of records per time point ranged from 1,980 (ADG90) to 1,283 (LFEC at 150 days of age). Traits were analyzed using a univariate model fitting fixed class effects of sex, birth/rear type, and season/system (fall or winter/conventional or organic), and fixed covariate of actual age at 90 days. Random effects included contemporary group, birth year, and an additive genetic effect whereby genetic relationships were captured through pedigree data. The heritability of FEC was 0.09 ± 0.03, 0.12 ± 0.03, and 0.07 ± 0.04, at 90, 120 and 150 days, respectively. PCV estimates were 0.22 ± 0.04, 0.32 ± 0.05, and 0.29 ± 0.06, at 90, 120 and 150 days, respectively. The heritability estimates of ADG were 0.09 ± 0.03, 0.12 ± 0.04, and 0.20 ± 0.04, at 90, 120 and 150 days, respectively and FAM were 0.15 ± 0.04, 0.10 ± 0.04, and 0.19 ± 0.05. Genetic and phenotypic correlations between GIN infection traits and ADG at the same time point were estimated using a bivariate model. The genetic correlation of LFEC with ADG was low for all timepoints analyzed and ranged from -0.07 ± 0.28 (150 days) to 0.07 ± 0.19 (90 days). Phenotypic correlations were similarly low and ranged from -0.02 ± 0.07 (120 days) to -0.16 ± 0.07 (150 days). LFEC showed a consistent negative genetic and phenotypic correlation with PCV at all timepoints, ranging from -0.17 ± 0.17 (90 days) to -0.57 ± 0.18 (150 days) and -0.32 ± 0.05 (90 days) to -0.20 ± 0.06 (150 days), respectively. Conversely, FAM was positively correlated with LFEC, with genetic correlation estimates ranging from 0.21 ± 0.22 (120 days) to 0.54 ± 0.20 (150 days) and phenotypic correlations ranging from 0.08 ± 0.06 (150 days) to 0.22 ± 0.05 (90 days). The genetic and phenotypic correlations of PCV with ADG increased over time, going from -0.17 ± 0.15 to 0.19 ± 0.18 and 0.08 ± 0.06 to 0.10 ± 0.06, respectively. The correlations of FAM with ADG were more variable, but generally low, ranging from -0.14 ± 0.06 (150-day phenotypic correlation) to 0.09 ± 0.18 (90-day genetic correlation). We showed that selection on PCV may be more effective than selection on LFEC to reduce the burden of GIN infection, although further investigation into its correlation with growth is warranted. This dataset will be used to investigate resistance, resilience, and susceptibility traits in Katahdin lambs.

241 Increased Inflammatory Tone and Impaired Skeletal Muscle Growth in Intrauterine Growth-Restricted Neonatal Lambs Is Improved By Daily Supplementation of ω-3 Polyunsaturated Fatty Acid Ca2+ Salts

Abstract Low birthweight due to fetal intrauterine growth restriction (IUGR) often results from maternofetal heat stress. IUGR fetuses exhibit enhanced inflammatory tone, which persists after birth and impacts body composition, skeletal muscle growth, and metabolic function. Therefore, our objective was to determine whether daily oral supplementation of Ca2+ salts of ω-3 polyunsaturated fatty acids (ω-3 PUFA) to IUGR-born neonatal lambs improved inflammatory tone, body composition, and growth metrics. Pregnant ewes were exposed to heat stress (40°C, 35% humidity, THI = 85) from d 40 to 95 of gestation to induce IUGR. Lambs were weaned at birth and hand-reared on milk replacer. Daily oral boluses of 0.5 mL molasses containing 0 or 0.42 g/kg bodyweight of ω-3 PUFA (Virtus Nutrition) were administered. Femoral catheters were placed at d 24 and lambs were necropsied at d 30. At birth, IUGR lambs (n = 8; 3.12 ± 0.34 kg) and IUGR+ω-3 lambs (n = 7; 3.67 ± 0.32 kg) were lighter (P &amp;lt; 0.05) than controls (n = 12; 4.28 ± 0.15 kg). Plasma TNFα concentrations were greater (P &amp;lt; 0.05) at birth for IUGR (557 ± 121 pg/mL) and IUGR+ω-3 lambs (437 ± 82 pg/mL) than for controls (213 ± 78 pg/mL). Plasma TNFα concentrations remained increased (P &amp;lt; 0.05) for IUGR lambs but not for IUGR+ω-3 compared with controls at 2, 3, and 4 wk of age. Adjusted 30-d bodyweights were lighter (P &amp;lt; 0.05) for IUGR lambs (9.83 ± 0.6 kg) but not for IUGR+ω-3 lambs (11.59 ± 0.4 kg) than for controls (12.35 ± 0.2 kg). Heart and brain weights were 17% and 6% lighter (P &amp;lt; 0.05), respectively, for IUGR lambs than for controls. Brain weight deficits were resolved in IUGR+ω3 lambs, but heart weights did not differ between IUGR and IUGR+ω-3 IUGR lambs. Crown circumference/ bodyweight, abdominal circumference/ bodyweight, and cannon bone length/ bodyweight (indicators of asymmetric body composition) were 11% to 15% greater (P &amp;lt; 0.05) for IUGR lambs than for IUGR+ω-3 lambs or controls. At necropsy, IUGR lambs had lighter (P &amp;lt; 0.05) whole hindlimbs (29%) and flexor digitorum superficialis (24%), soleus (36%), biceps femoris (25%), semitendinosus (24%), gastrocnemius (29%), and longissimus dorsi (26%) muscles compared with controls. Weight deficits were partially or fully resolved in IUGR+ω-3 lambs for whole hindlimbs and for all muscles but the soleus, which did not differ from IUGR lambs. These findings demonstrate that daily oral supplementation of Ca2+ salts of ω-3 PUFA reduced the enhanced inflammatory tone observed in IUGR-born offspring, which coincided with improved skeletal muscle growth and indicators of symmetrical body composition.