Lamb Growth Research Articles

357 Effect of Energy Supplementation on Growth, Health, and Carcass Traits of Pasture-raised Lambs

Abstract Energy is often the most limiting nutrient in pasture diets. The effect of energy supplementation on the growth, health, and carcass traits of pasture-raised lambs was investigated. Seventy-nine Katahdin ram lambs were delivered to the Western Maryland Research & Education Center on June 15. After an 11-d acclimation period, lambs were allocated to two treatment groups based on age, weight, birth type, and FEC. Lambs in the PASTURE group (n = 40) rotationally grazed 2 ha of high quality, mixed pasture for 102 d. Lambs in the SUPPL group (n = 39) grazed similar pastures and were hand-fed a daily energy supplement (450 g of whole barley). The groups were handled bi-weekly to determine body weights, FAMACHA©, BCS, and dag scores. Individual fecal samples were collected upon arrival and at two additional time points. Lambs were ultrasound scanned on Sept 25 to determine carcass traits. Data were analyzed using the MIXED procedure of SAS, with statistical significance set at P ≤ 0.05. ADG varied considerably among weigh periods. Standard deviations were typically quite large, indicating wide variation in individual performance. Overall, the SUPPL lambs had higher ADG (P < 0.01), more backfat (P < 0.03), and higher BCS (P < 0.01) than the PASTURE lambs. There were no statistical differences in starting weight, ending weight, and loin depth. While internal parasites were not a problem during the study (only one lamb had a FAMACHA© score >4), PASTURE lambs had lower FEC (P < 0.05) on August 17 (240 ± 81 vs. 468 ± 80 epg). The value of additional gain (0.9 kg) would not have covered the cost of feed; however, four lambs were removed from the PASTURE group (due to death or failure to thrive) whereas only two lambs were removed from the SUPPL group. The study will be repeated in 2021 with similar lambs and protocol.

PSII-B-26 Comparison of Suffolk and Texel sired lamb growth and satellite cell proliferation in the early postnatal period

Abstract Suffolk ewes (n = 26) were blocked by body condition and weight, and randomly divided into two breeding groups (n = 13/group). One group was bred to a Texel ram and the other to a Suffolk ram. Ewes were confirmed pregnant by ultrasound and went to term. Male lambs (n = 4/sire/time) were harvested on d 2, 14, and 203 of age for muscle characterization and satellite cell isolation. From d 2 to 14, body weight increased (P < 0.01) by 80%, weight of the longissimus increased by 160%, and longissimus muscle area increased by 100%. Between d 14 and 203 lamb weight and weight of the longissimus increased by 350%, while longissimus area only increased by 100%. Sire breed did not alter lamb weight or weight of the longissimus (P > 0.10). Longissimus muscle area tended (P < 0.10) to be increased for Texel sired lambs when compared to Suffolk sired lambs. The total number of satellite cells isolated were not different by sire breed but did differ by animal age (P < 0.01). Satellite cell populations per gram of tissue increased between d 2 and 14 and decreased from d 14 to 203. Due to the large changes in growth from d2 to 14, satellite cell proliferation was examined at d 2 of age. Satellite cell proliferation capacity was altered by sire breed at d 2 of age potentially contributing to the increased longissimus muscle area. Advancing animal age and development alters satellite cell population numbers and potentially supports a high capacity for growth.

358 Effect of Molasses Type on Pre-weaning Lamb and Ewe Performance

Abstract The objective of this study was to investigate the effects of form of molasses on lamb and ewe performance. Creep feeding of lambs is essential to lamb growth, rumen development, and reduction of milk production from dams. Molasses is often added for increased palatability and energy. Crossbred lambs (n = 47; average age = 30 d) and their accompanying dams (n= 35) were assigned to one of two treatments using a completely randomized design with similar distributions of single and twin-born lambs and sexes. Treatment diets were formulated to be isonitrogenous and contained either wet (WMOL) or dry (DMOL) molasses. Dry molasses was added at 10% of the diet DM, whereas, wet molasses was added at 14.3% of the diet DM. Lambs were fed creep rations for 42 d prior to weaning. Creep feed was provided ad libitum and mixed grass hay was offered free-choice. Lamb weights were recorded weekly until weaning (d 42) and ewe BCS was measured at d 0 and d 42 (weaning). Overall lamb ADG was comparable (DMOL = 0.268 kg/hd, WMOL = 0.293 kg/hd; P = 0.30). Lamb weaning weights were similar between DMOL and WMOL (DMOL = 27.9 kg; WMOL = 27.5; P = 0.79). Ewe BCS was similar (P = 0.88) between DMOL and WMOL at 1.4 and 1.4, respectively. Estimated creep intake was calculated based upon total consumption following the end of the project and was found to be similar between treatments (DMOL = 0.54 kg/hd/d; WMOL = 0.59 kg/hd/d). Lamb pre-weaning growth and ewe performance was similar between DMOL and WMOL. Further research is needed to further explore the economic impact and use post-weaning.

Effects of Increased Growth Rates Prior to the First Breeding as Ewe Lambs and Pregnancy Rank on Mammary Glands of Two-Year-Old Ewes

This study investigated potential carry-over effects of increased growth rates prior to breeding at seven months of age on mammary glands of two-year-old ewes bearing one or two lambs, and examined the association between ewe mammary structures and the growth of their progeny. Ewe live weight and mammary ultrasound measures were recorded at 119 days of pregnancy, 29 days of lactation (L29), and weaning of the progeny (L79) in 64 two-year-old ewes selected from two treatments. The heavy group (n = 32) was preferentially fed prior to their first breeding at seven months of age, achieving an average live weight of 47.9 ± 0.38 kg. The control group (n = 32) weighed an average of 44.9 ± 0.49 kg at breeding. Lambs (n = 74) were weighed at birth, L29 and L79. Udder ultrasound measures did not differ (p > 0.10) between treatments, indicating no carry-over effects of treatments on mammary glands of two-year-old ewes. The association between ultrasound measures and lamb growth seemed to differ depending on lamb birth rank. More research is needed to further investigate these associations and determine whether ultrasonography could be used to identify ewes whose progeny would have greater growth rates based on birth rank.

Voluntary intake, milk and colostrum production and lamb growth when ewes are fed high-NaCl diets during pre- and post-lambing

Nutritional requirements at the end of gestation in ewes carrying multiple fetuses are rarely fully met in pasture production systems. Thus, concentrate feeds entail an alternative for increasing herd productivity. However, daily offer of complementary feed in extensive livestock production systems is not always possible due to climatic or geographic constraints or to labor shortages. One alternative is to offer large amounts of concentrate feed with the addition of NaCl that limits voluntary consumption, eliminating the need for daily supplement delivery. Our objective was to evaluate the effect of high salt levels added to concentrate feed on pre- and post-lambing twin-gestating ewes and their responses on feed intake, colostrum and milk production and composition, plasma biochemical profile variation and lamb growth. Twenty-four adult Corriedale females were housed in individual stalls and divided into four treatments: S13: ad libitum concentrate feed plus 13 % of salt; C13: the same amount of concentrate feed consumed by S13 ewes the day before, but without salt; S17: ad libitum concentrate feed with 17 % of salt, and C17: the same amount of concentrate feed consumed by S17 ewes the day before, but without salt. Fresh water and forage were offered in ad libitum amounts. Treatments were applied in the period of highest ewe nutrient demand, from day 123 of pregnancy to day 21 of lactation. The four percentage points in salt content resulted in a decrease of organic matter daily intake of concentrate (23 % of reduction in pre-lambing and 35 % of reduction in post-lambing for S17 relative to S13; P = 0.0134 and P = 0.0164, respectively). Lamb birth weights were similar between S13 and C13 (P = 0.1002) and between S17 and C17 (P = 0.8449) treatments. Colostrum and milk production did not differ between S13 and C13 (P = 0.9776 and P = 0.8928, respectively) or between S17 and C17 groups (P = 0.4943 and P = 0.7705, respectively). Plasma insulin, hematocrit and total protein levels were not influenced by the treatments and these parameters remained within normal physiological limits. Thus, the addition of 13 or 17 % of salt to concentrate feed did not affect the reproductive capacity of ewes or offspring growth, showing that ewes are able to withstand high doses of NaCl and supporting the potential of salt as a limiter of voluntary intake in pre- and post-lambing diets.

Growth performance, nutrient digestibility, blood parameters, and carcass characteristics by lambs fed an oregano and cobalt blend

Shifting ruminal fermentation via feeding a blend of oregano (Organum vulgare L.) essential oils and Co-lactate (EOC; Rum-A-Fresh, Ralco, Inc. Marshall, MN) could improve lamb growth and carcass performance. Eighteen Suffolk × Little Han Tail F1 male lambs (20.3 ± 0.23 kg BW and approximately 3 months old) were randomly assigned using a completely random design to one of three treatments. Treatments were (1) EOC0: basal ration without EOC, (2) EOC4: basal ration plus 4 g/d EOC, and (3) EOC7: basal ration plus 7 g/d EOC. Initial and 24 d BW was similar (P > 0.10), but at 48 and 72 d, lambs fed EOC7 demonstrated greater (P = 0.01) BW compared with EOC0 fed lambs, while lambs fed EOC4 were intermediate and similar (P > 0.05). Average daily gains (ADGs) for 0–24 and 0–72 d were greater (P < 0.05) for lambs fed EOC4 and EOC7 compared with lambs fed EOC0, while DM intake was similar (P > 0.10). Feed conversions for 0–24 d were improved (P < 0.02) for lambs fed EOC4 and EOC7 compared with lambs fed EOC0. However, 0–72-d feed conversions were greater (P < 0.01) for lambs fed EOC7 compared to lambs fed EOC0, with lambs fed EOC4 being intermediate and similar (P > 0.05). DM, NDF, and ADF digestibilities were similar (P > 0.10) among treatments, while CP digestibility was greater (P < 0.01) for lambs fed EOC4 and EOC7 compared with lambs fed EOC0. Carcass weight and dressing percentages were improved (P < 0.01) for lambs fed EOC7 compared with lambs fed EOC0 and EOC4. Head width was greater (P > 0.01) for lambs fed EOC7 compared with lambs fed EOC0 and EOC4, while rump width was greater (P > 0.01) for lambs fed EOC4 and EOC7 compared with lambs fed EOC0. Plasma triglyceride and cholesterol concentrations were lower (P < 0.05) for lambs fed EOC4 and EOC7 compared with lambs fed EOC0, while albumin, total serum protein, and glucose concentrations were greater (P < 0.05) for lambs fed EOC4 and EOC7 compared with lambs fed EOC0. Feeding an EOC blend as an alternative antibiotic growth promoter at 4 and 7 g/d linearly improved lamb growth performance, feed conversions, frame growth, carcass weights, dressing percentages, and immunity.

Delayed weaning improves the growth of lambs grazing chicory (Cichorium intybus) pastures

The Midwestern United States is characterized by summers with limited precipitation and as such pastures mature and feed quality decreases from mid to late summer. The poor forage quality impedes sheep production at weaning. Alternative forages such as chicory have been shown to maintain forage quality for a greater time compared to grass pastures and may increase body weight growth of weaned lambs. To improve system efficiency producers may consider delaying lamb weaning age to improve the growth and health of pasture-reared lambs if forage quality can be maintained. The objective of this experiment was to investigate the effects of delayed weaning on the growth and health of lambs grazing chicory (Cichorium intybus). We hypothesized that delaying lamb weaning age would increase lamb body weight and improve parasite resilience. A total of 18 cross-bred ewes and 36 cross-bred lambs (25.2 ± 0.5 kg) were stratified by weight, sex, and randomly assigned to one of two weaning treatments: 1.) lambs weaned at 60 days of age (control) and 2.) lambs, 60 days of age, remained with their dam and weaned at 116 days of age (delayed weaned). Delayed weaning resulted in greater weight gains as delayed weaned lambs were heavier on days 42 and 56 of the grazing period when compared with control lambs. In addition, delayed weaned lambs had a greater average daily gain (ADG) on days 14 and 42 of the grazing period and overall ADG when compared with control lambs. In monitoring lamb health, there were no differences in lamb FAMACHA© eye score, packed cell volume, fecal egg count, and total plasma protein concentration. Delayed weaning has shown to be beneficial in improving lamb growth; however, within the context of the current study delayed weaning did not improve lamb parasite resilience.

Evaluation of tall fescue cultivars containing endophytes on pasture productivity and lamb performance

Tall fescue (Lolium arundinaceum (Schreb.) Darbysh) is a valuable perennial pasture species, the productivity of which is increased by infection with endophytic fungi. However, toxins produced by the endophyte can cause fescue toxicoses, which are potentially detrimental to animal growth and health. It is desirable therefore, to develop non-ergot alkaloid producing endophytes which are not harmful to livestock. The purpose of this study was to compare cultivars of tall fescue with or without novel endophytes for their effect on lamb growth and productivity. Five tall fescue cultivar or endophyte treatments were sown into a randomised block design including three replicates. The treatments were Martin 2 (Mart; no endophyte, acting as a positive control), Kentucky-31 (KY-31; containing wild endophyte and acting as a negative control), Martin 2 with novel endophyte Protek™ (Mart Protek™), Tower with endophyte Protek™ (TowerProtek™) and DuraMax fescue with endophyte Series 9 (DuraMax 9). When established, composite lambs were allocated to the 15 plots and grazed the irrigated pastures in two successive periods of 42 (n = 150 lambs; summer) or 65 days (n = 150 lambs; autumn) between January and May 2012. Herbage quality was similar between treatments. Ergovaline was detected at low levels (<0.2 ppm) only in herbage from KY-31 plots. Lambs grazing novel endophyte treatments (Protek™ and Series 9) produced similar growth rates over both grazing periods to those grazing Martin 2 without endophyte (Mart). There were no treatment effects on the rectal temperatures of lambs within sampling dates. Plasma prolactin levels were lower (P < 0.05) for lambs grazing KY-31 (77 ng/mL and 4 ng/mL in the summer and autumn grazing periods, respectively) and DuraMax 9 (99 ng/mL and 13 ng/mL in each grazing period, respectively) treatments than those grazing other treatments, in both grazing periods. Endophyte Protek™ did not produce ergot alkaloids in sufficient quantities to limit lamb growth or suppress plasma prolactin levels. Based on plasma prolactin levels, the Series 9 endophyte may present a risk for fescue toxicoses, although further evaluation is required using genetic verification of endophytes. Lamb health and growth may not be reduced when grazing tall fescue with known toxic endophytes if weather conditions do not reach levels that induce heat stress. Some novel endophytes may pose toxicoses risk, so selection of pastures with an appropriate level of risk for the climate and animal management system will minimise risk.

Milk replacer and linseed supplementation promotes puberty and semen quality in growing male lambs

• The strategic supplementation with energy and protein-rich feed-stuffs, containing health beneficial fatty acids may improve growth and reproduction performance in male lambs. • Protein rich milk replacer feeding during the pre-weaning and linseed supplementation during the post-weaning enhanced growth, testicular development and advanced the age of puberty in ram lambs. • Milk replacer feeding during the pre-weaning and linseed supplementation during the post weaning increased sperm concentration and rapid motility of spermatozoa in ram lambs. Feeding nutrient rich diets with functional properties enables accelerated growth and improves reproductive function in animals. In this experiment protein rich milk replacer was supplemented during the pre-weaning and n-3 PUFA rich linseed during the post-weaning to assess their effect on puberty and reproduction in Malpura ram lambs. Fifteen-day old male lambs of Malpura breed (n = 18) were equally divided into two groups. The lambs in one group were allowed to suckle their dam upto 3 months age and were fed standard control diet (CON) that included concentrate, Vigna unguiculata hay, Zizyphus nummularia and Ailanthus excelsa leaves up to six months age. Lambs in another group were supplemented milk replacer and linseed (MR-LIN) in a regimen of milk replacer at 100 mL/lamb/day for the first two weeks, then 250 mL/lamb/day until weaning, and subsequently, concentrate with 10 % crushed linseed. Testicular measurement and semen quality assessment of lambs were started at the age of five months. The average daily gain of milk replacer supplemented lambs up to weaning was 22.4 % higher (P = 0.07) than the CON lambs. The testicular attributes i.e. testicular length, breadth, volume and scrotal circumference were significantly higher (P < 0.01) in lambs of MR-LIN group. The puberty was hastened significantly (χ 2 df1 = 4.853, P = 0.046) in MR-LIN group in which 88.9 % of lambs attained puberty by age of 10 months in contrast to 55.6 % lambs in CON group. Sperm concentration, mass motility, percent of rapid motile spermatozoa were significantly higher (P < 0.05) in MR-LIN supplemented lambs than those of CON. Protein rich milk replacer feeding during the pre-weaning and n-3 PUFA rich linseed supplementation during the post-weaning period enhanced growth and testicular development and advanced the age of puberty in growing ram lambs.

Effects of Sunflower Hulls on Productive Performance, Digestibility Indices and Rumen Morphology of Growing Awassi Lambs Fed with Total Mixed Rations.

Forty-eight growing Awassi lambs were used in a 70-day trial to investigate the effects of different levels of dietary sunflower hulls (SFH) on growth, rumen morphology, fiber digestibility and meat characteristics of lambs. Animals were randomly allocated to 4 groups with 3 replicates of 4 lambs each. The diet was composed of total mixed ration (TMR) without SFH (control group), and the TMR diet supplemented with SFH at a level of 5% (SFH5), 10% (SFH10) and 15% (SFH15). Lambs in the treatment groups had greater BW changes (p = 0.04) and ADG (p = 0.04) than the lambs in the control group. Intake of dry matter, acid detergent fiber (ADF) and neutral detergent fiber (NDF) were also significantly (p < 0.05) higher in SFH15 compared to SFH10. Digestibility of ADL and empty stomach weight were also significantly (p < 0.05) higher in SFH10 and SFH15, respectively. Cooking loss, blood total cholesterol and total protein decreased significantly (p < 0.05) in SFH15. Ruminal lightness (L) and yellowness (b) also increased significantly (p < 0.05) in SFH15. We concluded that the TMR diet supplemented with up to 15% SFH improved weight gain, digestibility, meat cooking loss and rumen color in Awassi lambs.

The effect of behavioral reactivity on maternal behavior and offspring growth performance in Norduz ewes

The aim of this study was to determine the effect of behavioral reactivity on maternal behavior of ewes and early postnatal behavior and growth in lambs until weaning. The study was carried out with 100 multiparous Norduz ewes and 30 lambs. The study began by performing arena and scale tests and determining the test cortisol level in ewes during the anestrus period. Then, ewes were divided into two groups according to test reactivity as either “reactive” or “proactive” by using hierarchical cluster analysis. On the 50th day after mating, 15 reactive and 15 proactive gestating ewes of similar live weight, body condition and age (54.5 ± 0.58 kg, 3.19 ± 0.023 points and 4.07 ± 0.089 years, respectively) and carrying a single fetus each were selected and placed in one of two groups. Behavior of ewes and lambs from each group were monitored for a 3 -h period post-partum and the ewe-lamb separation test was performed within first 3 days postnatal. Ewes were phenotyped according to grooming duration, number of bleats, leaving lamb, preventing sucking etc., while lambs were phenotyped based on number of successful sucks, bleats, total suck duration, etc. Growth was determined by recording live weights of lambs at 2-week intervals until the 90th day. The whole trial lasted a total of 9 months. Ewes grazed entirely on rangeland with no extra feed supplementation. Ewes were fed with alfalfa hay and gradually supplemented with barley and concentrate during the winter. Serum cortisol levels were found significantly different in reactive and proactive ewes (1.57 ng/ml and 0.86 ng/mL, respectively; p < 0.001). During the early postnatal period, more high-pitched bleats were counted for proactive ewes, who also left their lambs alone more often than reactive ewes (p < 0.01), whereas reactive ewes had higher scores for following during ewe-lamb separation tests (p < 0.05). Lambs of reactive ewes had a higher total number of successful sucks, longer sucking duration (p < 0.05), and better growth performance at day 30 and day 45 (p < 0.05) as compared to lambs of proactive ewes. However, the weaning weights of reactive and proactive lambs were found similar as 30.3 ± 1.01 vs 30.2 ± 0.71 kg, respectively. In sum, the results of the present study indicated that some early postnatal ewe-lamb behaviours, ewe-lamb separation test score and lamb growth may be associated with behavioral reactivity. Given these findings, it was concluded that behavioral reactivity has potential use in efforts to improve maternal care and lamb welfare.

Genes and Pathways Affecting Sheep Productivity Traits: Genetic Parameters, Genome-Wide Association Mapping, and Pathway Enrichment Analysis

Ewe productivity is a composite and maternal trait that is considered the most important economic trait in sheep meat production. The objective of this study was the application of alternative genome-wide association study (GWAS) approaches followed by gene set enrichment analysis (GSEA) on the ewes’ genome to identify genes affecting pregnancy outcomes and lamb growth after parturition in Iranian Baluchi sheep. Three maternal composite traits at birth and weaning were considered. The traits were progeny birth weight, litter mean weight at birth, total litter weight at birth, progeny weaning weight, litter mean weight at weaning, and total litter weight at weaning. GWASs were performed on original phenotypes as well as on estimated breeding values. The significant SNPs associated with composite traits at birth were located within or near genes RDX, FDX1, ARHGAP20, ZC3H12C, THBS1, and EPG5. Identified genes and pathways have functions related to pregnancy, such as autophagy in the placenta, progesterone production by the placenta, placental formation, calcium ion transport, and maternal immune response. For composite traits at weaning, genes (NR2C1, VEZT, HSD17B4, RSU1, CUBN, VIM, PRLR, and FTH1) and pathways affecting feed intake and food conservation, development of mammary glands cytoskeleton structure, and production of milk components like fatty acids, proteins, and vitamin B-12, were identified. The results show that calcium ion transport during pregnancy and feeding lambs by milk after parturition can have the greatest impact on weight gain as compared to other effects of maternal origin.

Influence of clipping of North Caucasian Meat and Wool breed sheep before lambing on wool productivity of ewes and their offspring

Over the past 20 years, various scientists have conducted a number of researches on the effect of clipping before lambingon the wool productivity of sheep of different breeds and in different climatic conditions. The authors studied the effect of clipping before lambing on the milk production of ewes, studied the growth and development of lambs, the dynamics of live weight and the livability of young animals. The accumulated data allowed us to conclude that the use of clipping before lambing increases the productive performance of animals. However, these studies were fragmentary and did not have a systematic nature, so for these and other reasons they were not adopted by sheep breeders. The work on the infl uence of clipping before lambingon the wool productivity of the sheep of North Caucasian Meat and Wool breed has been carried out in the experimental division of the All-Russian Research Institute of Sheep and Goat Breeding. The purpose of the research was to determine the effect of late-autumn (November) insemination and clipping before lambing (3 weeks before lambing) of the sheep of North Caucasian Meat and Wool breed on the quality characteristics of the wool of ewes and their off spring. In accordance with the research methodology 2 groups of pregnant ewes have been selected, the formation of which has been carried out on the principle of analogues in age and live weight. In the 1st group (control) 100 heads were selected and have been clipping in the traditional terms after lambing (early June), in the 2nd group (experimental) 100 heads that were clipping three weeks before lambing (early April). It has been found in our studies that clipping ewes 21 days before lambing has a positive effect on the wool productivity of the resulting off spring. As the result of better growth and development of young animals, more intensively receive nutrients to the hair follicles, so most of them produce wool fiber.

Associations among Mammary Ultrasound Measurements, Milk Yield of Non-Dairy Ewe Lambs and the Growth of Their Single Lambs.

Simple SummaryMammary internal structures were associated with milk yield in mature dairy ewes and lamb growth in ewe lambs. This experiment was designed to examine the association between mammary ultrasound measurements and milk yield in ewe lambs and the accuracy of using mammary ultrasound measurements to predict single lamb growth rates to weaning. Mammary internal structures were measured in 45 single-bearing ewe lambs at day 110 of pregnancy, week three (W3), five (W5), and seven (W7) of lactation and at weaning (L69). The ewe lambs were milked once at W3, W5 and W7 and the single lambs were weighed at birth, W3, W5, W7, and L69. The predictions of milk yield were moderate, and the predictions of lamb growth were high to moderate, indicating that mammary ultrasound was more accurate in predicting lamb growth than milk yield. Further investigations are required to identify better indicators of milk yield in ewe lambs.Mammary cistern size was positively correlated with milk yield of mature dairy ewes, but the association in ewe lambs is unknown. This experiment aimed to examine the associations between mammary ultrasound measurements and the milk yield of ewe lambs at one year of age and to determine the accuracy of using maternal mammary ultrasound to predict single lamb growth rates. Single-bearing ewe lambs (n = 45) were randomly selected and 30 were milked once at weeks three (W3), five (W5), and seven (W7) of lactation. Mammary ultrasound scans were performed at day 110 of pregnancy, W3, W5, W7, and weaning (L69). Single lambs (n = 30) were weighed at birth and at each mammary scanning event. Udder measurements explained 26.8%, 21.4%, and 38.4% of the variation in milk yield at W3, W5 and W7, respectively, and 63.5% and 36.4% of the variation in single lamb growth to W3 and to L69. This ultrasound technique was more accurate in predicting single lamb growth to W3 than milk yield and may enable the identification of pregnant ewe lambs whose progeny would have greater growth rates. More research is needed to identify accurate indicators of superior milk yield and determine whether ultrasound could be used to select ewe lambs.

Effect of Folic Acid by injection and supplementary on growth and puberty of Karadi male lambs.

The present study is carried out to study the effect of Folic Acid (FA) by injection and supplementary on animal body weight gain, Testes volume before slaughtering, Testes volume after slaughtering, Testosterone concentration in blood, and FA concentration in blood. Twenty-five (25) Karadi male lambs five months aged and the average weight was 24.54 ±1.92 kg were used in this experiment. The animals weighed after three months of treatment to get animal increased live weight, The testes measured after one, two, and three months of treatment to calculate testes volume, testosterone, and FA concentration level in the blood were taken after one, two, and three months of treatment. The present study demonstrated that animal body weight, animal body weight gain, and total body weight gain significantly not increased (p&gt;0.05). Testicular length, and testicular circumference not increased (p&gt;0.05) after 1st, 2nd, and 3rd months after treatment, and after slaughtering. However, testicular high increased (p&lt;0.05) after each month of treatment and slaughtering. Testosterone concentration in the blood significantly not different (p&gt;0.05) reported between treatments after the 1st, 2nd, and 3rd months of treatment. FA concentration in the blood significantly increased (p&lt;0.05) when used 3 and 6 mg FA by injection compared to control after 1st and 2nd months of treatment. However, blood FA concentration increased (p&lt;0.05) when used FA 6mg/ml as an injection after the 2nd month of treatment compared to control. While using FA by supplementation and injection significantly (p&gt;0.05) on the diameter and circumference of seminiferous tubules, germ cells thickness, and lumen diameters.

Associations between CYP17 gene polymorphisms, temperament and maternal behavior in ewes, and growth in their lambs

This study was conducted to determine temperament and maternal care classes, CYP17 gene polymorphisms, and cortisol status of a group of Norduz ewes. Additionally, the relationships between these factors, their effects on lambs survival and growth characteristics were investigated. A total of 72 ewes were subjected to arena and isolation box tests to determine their temperament classes. The distance the ewe retreated from the lamb during tagging was utilized to assess ewe maternal care classes. Ewes were genotyped for CYP17 628 SNP. Blood samples were collected between lambing and weaning to measure cortisol concentrations of ewes. The survival and growth data for the lambs of these ewes were recorded until weaning. Two temperament (low reactive and high reactive) and 2 maternal care classes (strong and moderate) were present. Two CYP 17 SNP 628 alleles (A and G) and 3 genotypes (AA, AG, and GG) were identified. For the distribution of CYP17 genotype frequencies within the population, the temperament or maternal care classes were not different (P > 0.05). The temperament of ewes did not affect maternal care in our flock. Positive partial correlations between cortisol and total cross, distance to stimulus, and sniffing were determined (P < 0.05). CYP17 genotype was an effective factor for some behavioral traits (i.e., total cross) and cortisol release (P < 0.001). Neither temperament (P = 0.636) nor maternal care classes (P = 0.985) differed with cortisol concentrations. CYP17 genotype, cortisol status, temperament or maternal care class of ewes did not affect birth or weaning weight of their lambs (P > 0.05). Although there was no significant relationship among CYP17 genotype, maternal care, and lamb survival and growth, the effect of CYP17 genotype on some behavioral traits and cortisol release was found to be significant. Further studies with larger animal populations are required to elucidate the possible use of CYP17 SNP 628 genotypes as genetic markers for temperament classification.

Modeling the Growth of Lambs in the Early Stages of Postembryonic Development

Improving the efficiency of the sheep industry is based not only on additional investments, but also on the use of modern methods of breeding and selection. A significant role is given to modeling and forecasting processes in sheep breeding. The article is devoted to the development of a model for the growth and development of lambs in the first months of their post-embryonic period, which contains a system of equations describing the energy, protein and nutritional needs of animals. This model takes into account the influence of environmental factors on the growth and development of lambs and the features of the formation of future productivity.

The effects of protein supplementation and pasture maintenance on the growth, parasite burden, and economic return of pasture-raised lambs.

The objective of this experiment was to evaluate the impact of protein supplementation and pasture contamination with gastrointestinal nematodes on the mitigation of parasitic infection in grazing lambs. We hypothesized that there would be no difference between protein supplementation and newly sown pasture in evaluating lamb growth and health parameters associated with parasitism. Furthermore, we questioned if there would be an interaction between protein supplementation and pasture type. A total of 192, 60-d-old lambs (28.3 ± 5.1 kg) were randomly assigned to one of four treatments: 1) new pasture without supplementation (NN); 2) new pasture with supplementation (NS); 3) established pasture without supplementation (EN); and 4) established pasture with supplementation (ES) and grazed for 112 d. Lambs were supplemented at a rate of 1% body weight/d. Supplemented lambs had greater body weight (BW) and average daily gain (ADG) when compared with non-supplemented lambs (P < 0.04). Additionally, lambs on newly sown pasture demonstrated greater BW and ADG when compared with lambs grazing on established pasture (P < 0.05). For lamb health, lambs in the EN treatment group had the greatest FAMACHA eye scores and lowest packed cell volume (PCV) over the course of the 112-d grazing period (P < 0.05). Moreover, NS and ES treatment lambs demonstrated similar FAMACHA eye scores when compared with NN treatment lambs; however, NN treatment lambs showed lower PCV when compared with NS and ES treatment lambs (P < 0.05). In evaluating fecal egg counts (FEC), lambs on new pasture or given supplement demonstrated lesser FEC when compared with those lambs on established pasture or not given supplement (P < 0.05). Sixty-four lambs were harvested to evaluate total abomasum nematode counts which demonstrated that Haemonchus contortus represented approximately 80% of total nematodes. Furthermore, based upon gross margin analysis, lambs given a protein rich supplement on pasture had a 9.3 kg increase in lamb BW whereas newly sown pasture had a 1.3 kg increase in lamb BW. A protein rich supplement given to lambs grazing pastures contaminated primarily with H. contortus or placing lambs on newly sown pasture increases lamb BW and improves parasite resiliency. Selection of parasite management strategies may be influenced by cost of production and market opportunities.

Maternal caffeine administration to ewes does not affect perinatal lamb survival

Perinatal mortality of lambs is the major source of reproductive loss in extensive sheep production systems. Treatment with caffeine has reduced intra-partum mortality and/or improved metabolic indicators in other species following hypoxia. This study was conducted to evaluate the efficacy of caffeine for improving perinatal lamb survival. Experiment 1 comprised group-fed Merino ewes grazing pasture and offered 1.8 g/day (estimated 20 mg/kg live weight) caffeine throughout a 4-week lambing period, and a control without caffeine. The survival of lambs to marking (vaccinated, tail docked, males castrated) age in the caffeine treatment group (0.81) did not differ (P = 0.199) from that of control lambs (0.73; total born n = 877). Experiment 2 comprised Merino ewes lambing from three successive weekly joining groups. Treated ewes were drenched with an aqueous caffeine solution at a dose rate of 10 mg/kg live weight from the day before anticipated lambing, until the individual lambed. Control ewes were drenched with water. The proportion of lambs born dead (0.07) and the survival of lambs to marking age (caffeine 0.61; control 0.62) were similar between treatment groups (total born n = 1158). In both experiments, ewe mortality and the weight of lambs at marking were not altered by caffeine treatments. The results from this large-scale field study indicate caffeine is not an effective therapeutic agent to increase either intra-partum or perinatal survival, or lamb growth rates.

THE COMBINED EFFECT OF SUCKLING SYSTEM AND WEANING WEIGHT ON MILK TRAITS OF NATIVE SHEEP

Data of the current stud, were collected on 32 Iraqi native sheep aged 2-5 years maintained on commercial flock. At lambing, the 32 ewes were divided into two equal groups, lambs in the 1st group were left with their dams till weaning and then were milked twice daily till they dry off (Continuous), whereas the 2nd group, lambs were separated at night for 12 hr. and the ewes were milked once daily at morning (Restricted). Then each main group was subdivided into two group to be weaned their lambs when they reached 3 or 4 times of their birth weight (WB1 and WB2). Results revealed that ewes of restricted suckling produced significantly (P &lt; 0.05) more post weaning (80.80 vs.49.44 L), total milk yield (135.01 vs. 109.94 L) and sealable milk (99.86 vs. 49.44 L) and had significantly longer lactation period (169.3 vs. 140.2 days) compared ewes in continuous suckling. Also, results obtained indicate that daily gain in weight averaged 0.23 kg from birth to weaning and from birth to marketing and 0.24 kg from weaning to marketing and neither suckling system nor weaning weight affected these trait significantly. It can be concluded that restricted suckling resulted in an increase in sealable milk without any adverse effect on growth of lambs.