Lamb Live Weight Research Articles

Selection by Lambs Grazing Plantain (Plantago lanceolata L.), Chicory (Cichorium intybus L.), White Clover (Trifolium repens L.), Red Clover (Trifolium pratense L.) and Perennial Ryegrass (Lolium perenne L.) across Seasons.

Simple SummaryDiverse pastures based on combinations of the forage herb species plantain and chicory with red clover and white clover, provide superior annual feeding value to finish lambs in temperate regions, compared to the traditionally used perennial ryegrass and white clover pastures. The success of herb-clover diverse pastures is dependent on maintaining the relative abundance of each species in the mix over time. The selective grazing by lambs on herb-clover mixes was compared with their selection on perennial ryegrass and white clover pasture, by using randomly tagged individual plants, to determine if selective grazing changed the relative abundance of any of the herb or clover species. Variations in the selection of the forage species over the seasons of the year were observed, but best practice grazing management was shown to maintain the relative abundance of species in herb-clover pastures required for superior lamb live weight gains.Plantain (Plantago lanceolata) and chicory (Cichorium intybus) are now widely used in combination with clover species to provide greater annual lamb live weight gains than perennial ryegrass and white clover pasture. Reported selective grazing of the species in herb-clover mixes could potentially detrimentally change the relative abundance of species and decrease lamb production. Lambs were offered three herbage treatments: Pasture (perennial ryegrass and white clover) mix, plantain (plantain, red clover and white clover) mix and a chicory (chicory, plantain, red clover and white clover) mix in each of four seasons for two years. The experiment was a randomized complete block design with three replicates with 18–30 lambs per treatment replicate depending on the season. Lambs were rotationally grazed and fed ad libitum. Selection by the lambs of individually tagged plants within the pasture treatments was observed for three days on two occasions per season. Red clover was the most selected species on day 1, but by day 3 there was no difference in the selection of the species (p < 0.05). Plantain and chicory in the plantain and chicory mixes were selected less on day 1 in autumn relative to the other seasons (p < 0.05). It was concluded that three days of grazing before moving lambs maintained the relative abundance of species in the herb-clover mixes.

PSX-27 The influence of technological stress on the biochemical status of lambs with different genotypes

Abstract Sheep breeding is accompanied by various technological processes, some of them are stress factors, and one of these factors is the weaning of lambs from mothers. The goal was to study the effect of technological stress on the biochemical status and growth indicators of lambs with different genotypes. Lambs were divided into three groups: pure-bred Romanov (n = 18), Katahdin (n = 7) and Argali hybrids (¼Argali × ¾Romanov, n = 17). Before weaning and 15 and 30 days after weaning, the lambs live weight was determined and the blood serum biochemistry analysis was conducted. Statistical analysis of the data was performed using the SPSSv.23. The effects of genotype and technological stress on body weight and biochemical status are statistically significant (P ≤ 0.001). The live weight of the lambs before weaning was: Romanov 15.88±1.20kg, Katahdin 22.23±0.91kg, and hybrids 14.32±1.03kg. The differences between hybrids with Katahdins and Romanovs were 55% and 39.9% (P ≤ 0.05). The average daily gain (ADG) before weaning in Romanov lambs was 153.0±12.0g, Katahdins 203.0±8.0g and hybrids 119±11.0g. As a result of lambs weaning from mothers, technological stress was accompanied by an increase urea blood serum level in lambs. In hybrids it averaged 6.61mmol/L, which is 57% more than before weaning (P ≤ 0.05). In Katahdin, Romanov and hybrid lambs during the adaptation period was observed an increase the blood cholesterol level by 7.08%, 23% and 18% respectively, and ADG in all groups was decreased and amounted in hybrids 72±5.0g, in Romanovs 83±5.6g and in Katahdins 110±4.3g. The results of the study showed that the reaction of lambs to technological stress depends on the genotype of the animal, and the adaptation process after weaning is accompanied by a decrease in growth intensity. Supported by the Russian Science Foundation (project №18–16–00079) and the Ministry of Science and Higher Education of Russia (theme №АААА-А18-118021590132-9).

Effects of heavier live weight of ewe lambs at mating on fertility, lambing percentage, subsequent live weight and the performance of their progeny

ABSTRACT Ewe lamb live weight at first mating (7 months of age) is positively associated with reproductive performance and led to the recommendation of a minimum mating live weight of 40 kg. This experiment examined the effects of heavier mating live weight of ewe lambs on their live weight, fertility, lambing percentage and their progeny performance to weaning. Ewe lambs (n = 270) were randomly allocated to one of two treatments. The Heavy group (n = 135) was preferentially fed until mating, achieving 47.9 ± 0.36 kg, while the Control group (n = 135) had an average mating live weight of 44.9 ± 0.49 kg. Fertility, lambing percentage, ewe live weights, the survival and live weights of their progeny were recorded. There was a 28% increase in fertility and a 59% increase in lambing percentage in the Heavy group compared to the Control group. Progeny survival and live weights did not differ (P > .05) by treatment. A curvilinear relationship between fertility and ewe live weight at mating was identified, suggesting that ewe lambs should be mated at a live weight of 50–55 kg to maximise fertility and lambing percentage without reducing ewe live weight nor the progeny performance.

Phenotypic factors associated with lamb live weight and carcass composition measurements in an Irish multi-breed sheep population.

Understanding the phenotypic factors that affect lamb live weight and carcass composition is imperative to generating accurate genetic evaluations and further enables implementation of functional management strategies. This study investigated phenotypic factors affecting live weight across the growing season and traits associated with carcass composition in lambs from a multibreed sheep population. Four live weight traits and two carcass composition traits were considered for analysis namely; birth, preweaning, weaning, and postweaning weight, and ultrasound muscle depth and fat depth. A total of 427,927 records from 159,492 lambs collected from 775 flocks between the years 2016 and 2019, inclusive were available from the Irish national sheep database. Factors associated with live weight and carcass composition were determined using linear mixed models. The heaviest birth, preweaning, and weaning weights were associated with single born lambs (P < 0.001), however by postweaning, there was no difference observed in the weights of single and twin born lambs (P > 0.01). Breed class affected lamb live weight and carcass composition with terminal lambs weighing heaviest and having greater muscle depth than all other breed classes investigated (P < 0.001). Lambs born to first parity dams were consistently lighter, regardless of time of weighing (P < 0.001), while dams lambing for the first time as ewe lambs produced lighter lambs than those lambing for the first time as hoggets (P < 0.001). Greater heterosis coefficients (i.e., >90% and ≤100%) resulted in heavier lambs at weaning compared with lambs with lower levels of heterosis coefficients (P < 0.001). A heterosis coefficient class <10% resulted in lambs with greater muscle depth while recombination loss of <10% increased ultrasound fat depth (P < 0.001). Results from this study highlight the impact of multiple animal level factors on lamb live weight and carcass composition which will enable more accurate bio-economic models and genetic evaluations going forward.

Liveweight and carcass characteristics of White Dorper and Crossbred lambs grazing lucerne, subterranean clover, biserrula or a choice of subterranean clover plus biserrula in southern Australia

Context Biserrula (Biserrula pelecinus L.) is a relatively new legume species in Australia that has been shown to maintain higher quality forage late in the season than subterranean clover (Trifolium subterraneum L.). Aim This study investigated the suitability of lucerne (Medicago sativa L.), subterranean clover and biserrula, or a choice of both biserrula and subterranean clover, for finishing White Dorper and White Suffolk × Merino lambs during spring. Methods An experiment was established near Wagga Wagga, NSW, in 2013 in a randomised complete block design with three replicates and four pasture treatments grazed by lambs during late spring and early summer. Liveweight, carcass weight and GR fat depth of White Dorper and White Suffolk × Merino lambs grazing lucerne, subterranean clover, biserrula or a choice of subterranean clover plus biserrula were compared. Key results Lambs grazing lucerne had significantly (P &lt; 0.05) higher final liveweight, carcass weight and GR fat depth than lambs grazing other pasture treatments. After 61 days of grazing, mean liveweight of lambs grazing lucerne, subterranean clover and subterranean clover plus biserrula was higher than of lambs grazing biserrula monoculture. In vitro digestible organic matter digestibility and crude protein content indicated that lambs grazing biserrula should have achieved growth rates at least as high as lambs grazing subterranean clover. Sheep genotype and pasture type affected final liveweight. Final liveweight was higher for White Dorper lambs when grazing the subterranean clover plus biserrula treatment than the subterranean clover monoculture (45.6 vs 44.5 kg; P &lt; 0.05) but was similar for White Suffolk × Merino lambs grazing these treatments (47.3 vs 47.2 kg; P &gt; 0.05). Conclusions Provision of a companion species or mixture of species when lambs graze biserrula during late spring to summer appears to offer benefits for lamb growth rate over this period.

The Effects of Common Vetch Grain (Vicia Satıva) on Some Blood, Rumen Parameters and Rumen Protozoa in Lambs

This study investigated the effect of different levels of common vetch (CV) grain feed on some blood and rumen parameters and rumen protozoa in lambs consuming sainfoin hay (SH). In the study two-month-old weaned, SH consumed, 36.25 ± 2.49 kg average body weight (BW), twenty-four female lambs were used. Ration groups were established as follows; In the first group (C, control), 2% SH and 0.00% CV of the lamb's live weight (LW) were adopted while in the second group, 1.25% SH and 0.75% CV ( CVI) and in the third group, 0.5% SH and 1.50% CV (CVII) were adopted. Blood and rumen fluid samples were taken twice, once at the beginning of the study and once on the 30th day of the study. Although there were statistical differences in some of the parameters investigated in the study, all blood and rumen parameters were within the normal limits specified for lambs in the literature. In this study, it was concluded that feeding the lambs that are consuming SH with CV 1.5% of their live weight did not have a negative effect and the total ration can be formed using both SH and CV.

Pasture production, persistence of legumes and lamb growth in summer‐dry hill pastures

AbstractPasture legumes that persist under challenging agroecological conditions are crucial to ensure high lamb growth rates in dryland pastures. Pasture and lamb production from binary and diverse mixtures (Mix) of tall fescue (TF) with white clover (Whc), balansa clover (Bc), subterranean clover (Sc) and birdsfoot trefoil (Bft) were compared in a summer‐dry hill site in Corvallis, Oregon over a two‐year period. In 2018, all pasture combinations provided similar lamb liveweight gains (LWG, mean 177 g/day) in the first half of spring. Lambs in TF‐Bc and TF‐Mix pastures grew 31 to 41 g/day faster than those grazing TF‐Sc, TF‐Whc and TF‐Bft in the second half of spring (p &lt; .05). Overall, TF‐Bc and TF‐Mix had higher (p &lt; .05) legume contents (32% and 37% respectively) compared to other pasture combinations. In spring 2019, lambs that grazed the TF‐Mix and TF‐Whc pastures had higher LWG than those on other pastures (p &lt; .05). The superior lamb growth rates were associated with the higher legume content and pasture quality maintained into the late spring period. Overall, the legume content of all pastures decreased over the course of the two‐year trial, with the decline being substantial for balansa clover. The present study confirmed that a high legume content of pastures leads to greater lamb growth rates. Total annual yields of pastures that had greater legume contents were superior to others (p &lt; .05). Thus, a combination of self‐regenerating annual clovers with perennial legumes in pasture mixtures may ensure a higher legume content and longer persistence in dryland hill pastures.

Genetic Variability of Bharat Merino Sheep Derived from Pedigree Information

Background: The genetic variability in a population is the raw material for selection, because the estimation of genetic parameters depends on the variability present within the population. The pedigree analysis is a method to assess population genetic variability. An increase in the level of inbreeding disturbs the production performance of the animals. Hence, it is essential to assess the effect of inbreeding on production performance of the animals at regular intervals. The present study was conducted on data of Bharat Merino (BM) sheep with twin objectives of evaluating the population structure by pedigree analysis and possible effect of inbreeding on lamb growth and heritability estimates. Methods: The study was conducted on data consisting of a total of 9688 pedigree records of BM sheep born from 1975 to 2018 (43 years), out of which 9050 formed population reference (with both the parents known). ENDOG ver 4.8 program was used to generate different measures of genetic diversity. General Linear Model of SPSS 25.0 was used to ascertain the effect of inbreeding (Fi) or change in inbreeding (ÄFi) on the lamb live weights. Using animal model with software WOMBAT, single trait linear mixed model analyses were performed. The heritability estimates and breeding values were obtained by including or excluding the inbreeding coefficient in the model to observe how the estimates of heritability varied with inclusion or exclusion of the inbreeding coefficient. Result: Effective number of founders (fe) was 56, constituting 11.39% founders in the population reference, while the effective number of ancestors (fa) was 43.The genetic contribution of the 15 most influent ancestors explained 50% of the genetic variability in the dataset. The ratio fe/fa, representing the effect of population bottleneck, was 1.302. The average inbreeding coefficients for the whole pedigree was 2.36%, while it was 3.84% for inbred animals. It was found that the inbreeding coefficient (Fi) increased with the addition of each generation to the pedigree. The average relatedness coefficient was 4.53% between members of the population.The effect of individual inbreeding (Fi) or the change in inbreeding (DFi) was not significant on the lamb live weights, except the effect of individual inbreeding (Fi) on three-month body weight and average daily gain (0-3month) and of change in inbreeding (DFi) on three-month body weight. From the analysis of the pedigree data of Bharat Merino sheep, it was found that the most of the measures of genetic diversity were within acceptable limits and the pedigree data was reasonably well maintained. When inbreeding was accounted for in the model, there were reductions in h2 estimates as well as the estimates of breeding values for both 3WT and ADG1 and consequently there were changes in ranking of animals for both 3WT and ADG1.

Quantifying sheep enterprise profitability with varying flock replacement rates, lambing rates, and breeding strategies in New Zealand

Sheep sales are the major source of income for most New Zealand sheep enterprises. Terminal (meat breed) sires are used to increase lamb growth rates enabling lambs to be sold earlier at higher prices on a per kg basis. Their use in self-replacing flocks is generally constrained by requirements for purebred ewe lambs from which to choose ewe replacements. This study used a bio-economic system-dynamics model of a sheep enterprise to investigate use of terminal sires for a ewe flock with a range of ewe replacement and lambing rates. Values from New Zealand industry survey data were used to simulate a representative New Zealand North Island East Coast Hill Country sheep enterprise (self-replacing flock of 2182 mature breeding ewes with a stable flock size on 549 ha of pasture where 60.8% of feed was consumed by sheep). Three ewe replacement rates (20%, 25%, and 30% per annum), lambing rates (110, 130, and 150%; lambs weaned per ewe presented for breeding), and breeding strategies (no terminal sires; breeding the maximum possible proportion of mature ewes with terminal sires; and breeding half of the maximum with terminal sires) were modelled. Income from lamb sales increased with use of terminal sires, due to increased production of lamb liveweight for sale and lambs sold earlier for higher prices, resulting in greater sheep enterprise cash operating surplus (COS). Sheep enterprise COS increases, from no terminal sire use compared with maximum use of terminal sires, ranged from $3/ha to $101/ha. Larger increases in COS occurred with a higher flock lambing rate and lower ewe replacement rate, which allowed for terminal sire use over a greater proportion of the flock. Up to 65% of the flock could be bred with terminal sires while producing sufficient numbers of purebred ewe lambs from which to choose replacements. For an average North Island East Coast Hill Country sheep enterprise with a replacement rate of 25% and lambing rate of 130%, sheep enterprise COS increased by $15,021 with maximum use of terminal sires (45% of the mature ewe flock), compared with use of only maternal sires. Use of terminal sires increased annual sheep energy demand by up to 6% and changed the sheep feed demand profile, with increases in energy demand post-weaning in December mostly compensated for by subsequent reductions in demand following crossbred lamb sales in January.

Effect of grazing different forage systems prior to and during mating on the liveweight, condition score, conception and reproductive rate of maternal-composite ewe lambs

Context Economic modelling identified that mating of ewe lambs for lambing at 1 year of age has the potential to increase the profitability of sheep-production systems in south-western Victoria. In order to optimise reproductive rates, ewe lambs should weigh at least 35–40 kg, have a condition score (CS) of 3.0 at mating, and be gaining weight (100–150 g/day) during mating. However, typical perennial ryegrass (Lolium perenne L.) pastures in south-west Victoria do not support the attainment of these targets without additional supplementation. Aim Our research aimed to determine how grazing summer-active pastures or brassica (Brassica napus L.) forages affects the liveweight, CS, conception and reproductive rate of ewe lambs when offered before and during mating compared with a system using perennial ryegrass plus supplement. Methods A field experiment was conducted at Hamilton, Victoria, Australia, in 2014 and 2016 testing seven forage treatments replicated four times in a complete block design. The treatments were: canola (B. napus, two treatments of different cultivars), forage brassica, lucerne (Medicago sativa L.), chicory (Cichorium intybus L.), plantain (Plantago lanceolata L.) and perennial ryegrass. Key results Ewe lambs grazing canola or forage brassica had higher (P &lt; 0.05) liveweight gains during the pre-mating and mating periods than those grazing the perennial ryegrass treatment (148 vs 75 g/day in 2014, s.e.m. 17; 139 vs 54 g/day in 2016, s.e.m. 17). In 2014, spring-sown dual-purpose canola, lucerne and chicory resulted in higher (P &lt; 0.05) reproductive rates (144–151%) than the perennial ryegrass treatment (103%); forage brassica and plantain gave intermediate results (128% and 129%). Conclusion Brassica forages (including spring-sown canola), lucerne and chicory can support the attainment of key liveweight and CS targets for successful mating of ewe lambs in autumn. Implications Spring-sown canola is therefore a viable alternative forage for use by livestock producers in southern Australia and presents an opportunity to incorporate an alternative income stream in mixed-farming systems.

Wool and Meat Production of Khangil-type Trans-Baikal Sheep

The wool and meat production of Khangil-type fine-fleece sheep within the Trans-Baikal breed has been studied. It is ascertained that 33.5, 59.1, and 7.4% of sheep are assigned to elite, first class, and second class, respectively, according to the rank structure. Liveweights of fine-fleece rams, replacement rams, ewes, and ewe lambs of the Khangil type exceed the breed standard for liveweight by 28.9, 38.7, 30.0, and 18.9%, respectively, and the breed standard for washed-wool clip by 42.6, 24.0, 22.7, and 38.9%, respectively. Analysis of fine wool quality revealed that rams’ wool corresponds to grade 60, while the wool of ewes, ram lambs, and ewe lambs is grade 64. The wool comfort factor of 86.1% was highest in the rams. It was 6.1, 3.1, and 5.4% higher than that in replacement rams, ewes, and ewe lambs, respectively. Coefficients of correlation between the wool fineness and its crimp and between the fineness and the comfort factor were negative in all the sex and age groups. These coefficients were rather high. A positive correlation of mean intensity (r = 0.274–0.652) between the wool fineness and the comfort factor was revealed. The results of slaughtering the fine-fleece ram lambs at the age of 6 months for control purposes indicated their high meat production performance. Thus, slaughter weight, slaughter yield, meat at grade 1, and coefficient of meatiness comprised 16.7 kg, 46.3%, 91.0%, and 3.4, respectively.

The effect of reproductive loss on the performance of a research flock.

The reproductive performance of a sheep flock is dependent on a multitude of complex interacting factors. Achieving optimal flock performance requires knowledge of the reproductive steps and how these are linked and related to available measurements of the state and performance of the flock. The goal was to use previously collected data from a research flock that had undergone selection for fecundity (11,369 lambing records), to model the key reproductive steps affecting flock reproductive performance. The model was used to investigate how changes in liveweight, age, ovulation rate, number of fetuses at midpregnancy, number of lambs born, and birthweight affect the number of lambs weaned and the weaning weight of each lamb in this flock. The data available from the research flock were used to parameterize models of each reproductive step and assess the role of ewe age and premating liveweight on each reproductive step. These models were then linked together as a simulation tool to assess the role of different parameters on flock reproductive performance, which was defined as the total weight of lambs weaned per ewe exposed to the ram. Flock elasticities were calculated that characterize the relative importance of the effect of average premating ewe liveweight (0.81), average ovulation rate (0.33), variance in ovulation rate (-0.095), embryo survival (0.72), lamb survival (1.03), conception failure (0.35), and average ewe age (0.056) on the total kilograms of lamb liveweight at weaning per ewe exposed to the ram. The largest elasticity for lamb survival indicated that a 1% increase in lamb survival is expected to have a 1.03% increase in the total kilograms of lamb liveweight at weaning per ewe exposed to the ram in this flock. Assuming similar costs, interventions to increase lamb survival for this flock will provide the largest increase in the total kilograms of lamb liveweight at weaning per ewe exposed to the ram, which is a key metric of flock performance.

Maternal supplementation of twin bearing ewes with calcium and magnesium alters immune status and weight gain of their lambs

This study investigated the effect of supplementation of ewes with calcium (Ca) and magnesium (Mg) in late gestation and early lactation on the plasma mineral concentration, hormone profile and immunity responses of ewes and their lambs. Twin bearing ewes were allocated between four dietary treatment groups (n = 11 per treatment): control (0.33% DM Ca and 0.28% DM Mg); high Ca (0.72% DM Ca and 0.28% DM Mg); high Mg (0.33% DM Ca, 0.48% DM Mg); and high Ca+Mg (0.66% DM Ca and 0.47% DM Mg), offered as part of a whole ration. Ewes were fed the treatment supplement from around one month prior to lambing to one month after lactation. Blood and urine samples were collected at seven time-points: weekly starting at 5 weeks prior to lambing; within 12 h post lambing (+12 h); and then at fortnightly intervals at 2 week (+2 W) and at 4 week (+4 W) post lambing. Colostrum/milk samples from ewes and blood samples from lambs were collected at +12 h, +2 W and +4 W. Live weight of lambs were measured at +12 h, +2 W and +4 W.The plasma concentration of PTH, 1,25(OH)2D3 and 25(OH)D3 was lowest at +2 W (P ≤ 0.002). Ewes from the Ca+Mg group had the lowest mean concentration of 1,25(OH)2D3 than the other groups (P = 0.005). Magnesium supplementation improved the plasma Mg concentration over time in ewes (P < 0.001) and lambs from the control group had lower plasma Mg concentration compared to the treatment groups at +4 W (P = 0.001). Oxidative burst response in lambs supplemented with Ca tended to be greater at +4 W than the other groups at the same time point (P = 0.051) and Mg supplementation increased total antioxidant capacity (TAC) concentration in lambs (P = 0.040). The average daily weight gain of lambs was 204 g/lamb/d for the Ca group, 207 g/lamb/d for the Mg group, 245 g/lamb/d for the Ca+Mg group which were greater than the control group (148 g/lamb/d) (P < 0.001).Despite the normal concentration of Ca and Mg in the plasma, supplementation of ewes with Ca and Mg from one month prior to lambing to one month post lambing improved TAC concentration and weight gain in lambs.

Genetic analyses of live weight and carcass composition traits in purebred Texel, Suffolk and Charollais lambs

Lamb live weight is one of the key drivers of profitability on sheep farms. Previous studies in Ireland have estimated genetic parameters for live weight and carcass composition traits using a multi-breed population rather than on an individual breed basis. The objective of the present study was to undertake genetic analyses of three lamb live weight and two carcass composition traits pertaining to purebred Texel, Suffolk and Charollais lambs born in the Republic of Ireland between 2010 and 2017, inclusive. Traits (with lamb age range in parenthesis) considered in the analyses were: pre-weaning weight (20 to 65 days), weaning weight (66 to 120 days), post-weaning weight (121 to 180 days), muscle depth (121 to 180 days) and fat depth (121 to 180 days). After data edits, 137 402 records from 50 372 lambs across 416 flocks were analysed. Variance components were derived using animal linear mixed models separately for each breed. Fixed effects included for all traits were contemporary group, age at first lambing of the dam, parity of the dam, a gender by age of the lamb interaction and a birth type by rearing type of the lamb interaction. Random effects investigated in the pre-weaning and weaning weight analyses included animal direct additive genetic, dam maternal genetic, litter common environment, dam permanent environment and residual variances. The model of analysis for post-weaning, muscle and fat depth included an animal direct additive genetic and litter common environment effect only. Significant direct additive genetic variation existed in all cases. Direct heritability for pre-weaning weight ranged from 0.14 to 0.30 across the three breeds. Weaning weight had a direct heritability ranging from 0.17 to 0.27 and post-weaning weight had a direct heritability ranging from 0.15 to 0.27. Muscle and fat depth heritability estimates ranged from 0.21 to 0.31 and 0.15 to 0.20, respectively. Positive direct correlations were evident for all traits. Results revealed ample genetic variation among animals for the studied traits and significant differences between breeds to suggest that genetic evaluations could be conducted on a per-breed basis.

Effect of early shearing during gestation on the productive and reproductive behavior of female sheep offspring in their first 18 months of age

The research has shown the interesting contributions of shearing in mid-gestation on the performance of lambs from birth to weaning. Other studies have reported that shearing at early pregnancy influences the development of the placenta and lamb live weight at birth. However, there was a lack of information on the effect of early-prepartum shearing on the behavior of the offspring from weaning onward. This study evaluated the effect of shearing ewes at 50 days of gestation on the growth, reproductive behavior and response to a gastrointestinal parasite challenge in the female offspring from weaning to 18 months old. Fifty-seven Polwarth female lambs were used, 22 being singles and 35 twins born to ewes either shorn at 50 days of pregnancy (PS, n = 23) or shorn at 62 days postpartum (U, control, n = 34) resulting in four subgroups: single lambs born to PS ewes (n = 8), born to U ewes (n = 14), twin lambs born to PS ewes (n = 15) or born to U ewes (n = 20). All progeny were managed together under improved pasture with a minimum forage allowance of 6% live weight on dry basis. Body weight, body condition score and fecal eggs count were recorded every 14 days from weaning to 18 months of age. Concentrations of progesterone were measured weekly (from 4 to 10 months of age and from 14 to 18 months of age) to establish the onset of puberty. Ovulation rate at an induced and a natural heat (545 ± 1.0 and 562 ± 1.0 day old) was recorded. Prepartum shearing did not affect the age at puberty or the ovulation rate of female offspring, but those born as singles were more precocious ( P = 0.03) and heavier ( P = 0.02) at puberty than twin born lambs. Both the average value of parasite egg count ( P = 0.0 7) and the Famacha index ( P = 0.02) for the entire study period were lower in lambs born to prepartum shorn ewes than those born to postpartum shorn ewes. In conclusion, shearing at 50 days of gestation did not affect the growth or the reproductive behavior of female offspring. However, female lambs born from ewe shorn during gestation showed a better response to the parasitic challenge, and further research is required to confirm this.

Effects of Maternal Dietary Cottonseed on the Profile of Minerals in the Testes of the Lamb.

The use of cotton co-products in animal feed is restricted by the presence of gossypol, which is a toxic and highly reactive molecule of complex minerals. In mammals, part of the offspring phenotype is influenced by dam nutrition. The aim of this study was to investigate the effect of ewe diet, with and without cottonseed (gossypol), on the testicular development of lambs from birth to weaning through the assessment of lamb live weight (LW), macro and histological morphology of testes, and mass fraction of chemical elements by neutron activation analysis (NAA) and microprobe X-ray fluorescence spectroscopy, as well as the multielement distribution map in the testes. Eighteen lambs were used with an average LW at birth of 4 ± 1.0kg. All lambs were offspring of Santa Inês ewes, fed on ration either with or without cottonseed during mating, gestation, and lactation, thus forming two treatments: control group (C) without cottonseed and treatment group with cottonseed (G). The animals were weighed from birth to 60days of age, at fortnightly intervals. At 60days of age, the lambs were orchidectomized to collect their testes for macroscopy, histological, neutron activation, and X-ray fluorescence analysis. Besides dry matter (DM), protein, ether extract (EE), calcium (Ca), and potassium (K) were higher in the ewe milk from the C group compared with the G group (P < 0.05). Lambs from the C group showed higher LW from 45days onwards, as well as higher average daily gain when compared with the G group (P < 0.05). They also presented higher testicular weight, volume, length, width, as well as tubule and lumen diameters compared with lambs from the G treatment (P < 0.05). Multielementary NAA revealed higher mass fractions of rubidium (Rb), selenium (Se), and cesium (Cs) in the testes of lambs from the C group when compared with the G group, while G showed higher zinc (Zn) content (P < 0.05). No differences between treatments were found for element levels and distribution using X-ray fluorescence microanalysis (P > 0.05). In conclusion, the maternal cottonseed diet compromised performance and testes development of the lambs and reduce the content of Se in the testes.

Relationships between sheep liveweight production and dry matter yield for lucerne-based pastures in spring

A five-year dryland grazing experiment explored the relationship between sheep liveweight (LWt) production and dry matter (DM) yield of lucerne-based pastures in spring. In 2011, a randomised complete block experiment with a lucerne monoculture, a lucerne/brome mix and a lucerne/cocksfoot mix were established at Ashley Dene, Canterbury and replicated six times. Pastures were managed under dryland conditions. Ewes with twin lambs at foot grazed in spring and LWt production, DM yield and botanical composition were quantified.Regression analysis showed total DM feed on offer accounted for only 11% of the observed variation in spring LWt production. Subsequent analysis of the botanical composition of the three pastures showed total feed on offer in spring was unaffected by pasture treatment in four out of five years. However, yield of the lucerne component on offer was 77–230% greater in the monoculture than the mixes in Years 3–5. Brome yields declined from Year 3 and did not recover. By Year 5, weeds accounted for 41% of the feed on offer in spring in the lucerne/brome mix. Net spring ewe + lamb liveweight production increased at a rate equivalent to 246 kg LWt +71 kg LWt per tonne of lucerne DM on offer (R2 = 0.83). There was no effect of pasture type. Where possible lucerne should be established as a monoculture to maximise liveweight gain. A runout stand was overdrilled with a companion grass to extend the productive stand life. The loss of lucerne over time indicated renewal should be initiated within 2–3 years of oversowing to ensure LWt production is not compromised.

Effect of Milk Intake, Its Composition, and Fatty Acid Profile Distribution on Live Weight of Suckling Wallachian Lambs until Their Weaning

Simple SummaryMaternal milk represents a crucial source of nutrients provided to suckling lambs. We analyzed the properties of maternal milk relative to the live weight of suckling lambs, and confirmed positive impact of milk production, milk protein, and milk lactose on lambs growth intensity in general. Further analyses identified specific fatty acids contained in milk fat with positive effect to lambs live weight. Results highlighted important components of mother’s milk for optimizing lambs’ growth potential till their weaning.This study determined effects of milk production, milk components, or fatty acids (FA) profile on live weight of suckling lambs till their weaning. Live weight (LW, kg) of 42 purebred Wallachian lambs (from 33 ewes) was recorded during four control days with approximately 30-day intervals during rearing. At the same time, their mothers were examined for milk production (kg), milk fat (g), proteins (g), lactose (g), and fatty acids (%) contents. Results investigated using linear regression analysis showed 5.93 kg (p < 0.05) increase of lambs LW corresponded with 1 kg of ewe’s daily milk production increase during the observed period. Similarly, significant 0.13 kg or 0.11 kg increases of lambs live weight corresponded with 1 g increase of milk protein or milk lactose at this time. Milk with higher prevalence of trans-palmitoleic acid, trans-vaccenic acid, cis-vaccenic acid, linolelaidic acid, linoleic acid, or conjugated linolenic acid (CLA) significantly improved lambs LW. Moreover, significantly positive Pearson partial correlation between LW and trans-vaccenic acid (r = 0.305) or CLA (r = 0.347) indicated on genetic correlation between these traits. Therefore, milk (natural or artificially supplied) with higher distribution of these specified FAs could improve lambs’ LW.

Pregnancy and Litter Size, But Not Lamb Sex, Affect Feed Intake and Wool Production by Merino-Type Ewes.

Simple SummaryWe examined whether feed intake and wool production are affected by pregnancy, litter size, or lamb sex on Merino genotype ewes. We observed that feed intake was influenced during pregnancy and lactation by litter size; whereas, wool production was influenced by litter size, but not by the sex of the lambs during pregnancy.Two experiments (Australia and Mexico) tested whether feed intake (FI) and wool production (WP) are affected by pregnancy (PRG), litter size (LZ), or lamb sex (LS) in Merino-type ewes. In Experiment-1, ewes were either not pregnant (NPR; n = 6), or carrying 1 (PR1; n = 7) or 3 (PR3; n = 11) fetuses, were studied in individual pens. NPR ewes had lower (p < 0.02) FI throughout PRG and lactation (LAC), except around lambing (p < 0.001). Following lambing, FI increased in PRG ewes (p < 0.001) to double the values in NPR ewes. PRG reduced WP (p < 0.001); in PR3, WP was lower than for both PR1 and NPR (p < 0.001). WP decreased during LAC and was lower in ewes rearing lambs than in NPR ewes (p < 0.001). Experiment-2 used 48 pregnant ewes (28 bearing singles and 20 bearing twins). Dam and lamb live weights (LW) and body condition (BC) were recorded from birth to weaning at 60 d, and dam fleece weight (DFW) was measured at weaning (12 months growth). WP was higher in ewes bearing and rearing single lambs than in ewes bearing twins (p < 0.001). DFW was positively (p < 0.01) related to LZ, dam LW, and BC, but not to changes in dam LW during LAC, or to lamb weight at birth or weaning, or LW gain, or LS. In conclusion, FI was affected during PRG and by LZ during LAC, whereas WP was influenced by LZ, but not LS, only during pregnancy.

Genetic Resistance Against Scrapie Disease Related to Lamb Growth Performance Traits

Abstract The objective of the study was to identify the impact of selection on genetic resistance against scrapie disease related to lamb growth performance attributes for Suffolk, Kent, Charollais, and Texel lambs.The allelic genotypes were grouped according to the presence of scrapie resistant allele (ARR): ARR homozygotes, ARR heterozygotes, no presence of ARR allele. The influence of these groups on lamb live weight (LW), musculus longissimus lumborum et thoracis depth (MLLT), and back-fat thickness at 100 days of age was investigated using SAS software. No significant differences for Suffolk and Charollais breeds were detected. Significantly highest LW (34.41 kg) and MLLT (27.80 mm) were noticed for Kent ARR homozygotes lambs, while significantly lowest values were estimated at lambs with absent ARR allele (LW = 33.42 kg, MLLT = 26.68 mm). Significantly lower muscle depth (–0.69 mm) was detected for Texel ARR homozygote compared to ARR heterozygote lambs. As a result, we were unable to detect a consistent evidence for reduced growth performance traits in relation to genetic resistance against scrapie disease. However, the number of animals in some groups caused as a limiting factor. This can be a potential reason of opposed trends in Texel and Kent lambs.