Hair Sheep Research Articles

Efficiency of infrared pyrometer and infrared thermography for assessing body surface temperature in hair sheep

The objectives of this study were: (i) to verify and compare the coat surface temperature (CST) of regions of interest (ROI) measured through infrared pyrometer (IRP) and thermography (IRT) under two environmental conditions, to evaluate (ii) reliability and (iii) sensitivity of the two infrared equipments to the environmental effect. Twenty hair ewes (Ovis aries), multiparous, non-lactating, non-pregnant, with body weight 59.38 ± 6.23 kg and body score condition ranging from 2.5 to 4.5 were evaluated. All CST, in both infrared methods, were higher (P < 0.001) in the afternoon (2 to 3 p.m.), with the exception of eyes surface temperature (TSEY) from IRT, which was higher (P < 0.001) in the morning (8 to 9 a.m.). Regarding the infrared methods at different times (twice a day, morning and afternoon), of the day, CST values for all ROIs were significantly higher (P < 0.001) in thermography, regardless of the time shift, except for ear pinna surface temperature (TSE) and rectum surface temperature (TSR), which showed no significant difference (P > 0.05) between the infrared methods during the morning shift. The thermal environment significantly influences (P < 0.001) the surface temperature of various anatomical regions in both infrared methods. The correlation coefficients between IRT and IRP were moderate. The IRT is more sensitive to the thermal environment, as it presented higher canonical coefficients in the environmental variables. Among surface temperatures, eye surface temperature is the most influenced by variables in the thermal environment, especially THI. All three methods (digital thermometer-DT, IRT and IRP) showed >80 % of the data variation in the first two components. Using the DT, we observed an association between vaginal temperature (VT) and RT with air temperature (AT) and temperature humidity index (THI), which was similar to the infrared thermography pattern, in which all ROIs were highly correlated with AT and THI. The opposite was observed in the pyrometer, in which an association between eye temperature and RH and lower factor loadings of the other ROIs with AT and THI in the first component was observed. In conclusion, while IRP and IRT showed similar performance in the morning, IRT proved to be more accurate in the afternoon, demonstrating a higher success rate in classifying the group of origin. Therefore, it is concluded that IRT is more reliable than IRP in detecting surface temperature changes under high temperatures.

Adding gastrointestinal parasite resistance to the breeding objective in hair sheep: initial steps.

The U.S. Maternal Hair index was designed by the National Sheep Improvement Program (NSIP) to increase total weight of lamb weaned per ewe lambing (TW). Producers are interested in adding gastrointestinal nematode (GIN) resistance to this breeding objective since parasitism causes substantial economic losses. The NSIP provides producers with estimated breeding values (EBV) for post-weaning fecal egg count (PFEC), an indicator of GIN resistance. Our objective was to gauge the effects of including PFEC as another selection criterion and goal trait. Selection index theory was used to construct 11 indexes. First was a benchmark index with TW as the goal. Weaning weight, and number of lambs born and weaned, were selection criteria. An index was then designed with PFEC added as a selection criterion. In 9 more indices, PFEC was also included as a goal trait, where the economic value of TW was scaled relative to that of PFEC. PFEC received a scaled economic value of -1 with that of TW increasing from +1 to +5 at +0.5 increments. Selection criteria were modelled as EBV or phenotypes. Annual genetic responses in goal traits were predicted. The top 3% of males and 26% of females were selected. Breeding values and phenotypes were simulated for 200 lambs by Cholesky decomposition and used to generate index scores, with 100 replicates run. Concordances with the animals selected in the benchmark scenario were determined. Using EBV as selection criteria, TW increased by 1.46kg/yr in the benchmark scenario. However, unfavorably, PFEC increased by 2.24%/yr. When using phenotypic criteria, TW increased by 0.52kg/yr and PFEC by 0.28%/yr. Once added as a goal trait, PFEC decreased regardless of the scaled economic value of TW. However, responses in TW were also reduced, although less so as its scaled economic value increased. A scaled economic value of +3 for TW appeared reasonable over other choices with 79% of the emphasis placed on TW in the breeding objective. With EBV as selection criteria, PFEC declined by 7.96%/yr with 98% of the response in TW retained. Also, on average, 64% of males and 80% of females were chosen in common with the benchmark. With phenotypic selection criteria, PFEC declined by 5.13%/yr and 94% of the response in TW was retained; 61% of males and 80% of females were chosen in common with the benchmark. Implementing an index with scaled economic values of +3 for TW and -1 for PFEC would balance gains in TW with reductions in PFEC.

PSIII-20 The effects of vitamin E and/or C on parasite burden in hair sheep

Abstract Anthelmintic resistance in flocks is an occurring issue for small ruminant producers due to increasing gastrointestinal nematode (GIN) infections. Prevalence of high virulence GINs decreases immunity and growth, therefore not making anthelmintics economically sustainable for producers. In this current research study, we examined the role of vitamins E and/or C supplemented to crossbred hair sheep (Dorper, Katahdin, Barbados crosses) on parasite burden over time. The hypothesis of this research was that supplementing vitamin E and/or C will work comparable to anthelmintic treatment to control GIN in hair sheep. Mature ewes (n = 30) were stratified based on FAMACHA score. Ewes were placed into one of five treatment groups: 1) no dewormer or vitamin treatment (CON; n = 6), 2) anthelmintic treatment (Levamed; 0.08mg/kg; Bimeda Animal Health, Schaumburg, IL; n = 6), 3) combination of vitamin E and vitamin C (Vitamin E300; 0.33IU/kg of body weight (BW) administered subcutaneously; Durvet Animal Health; Blue Springs, MI; Vitamin C; Orally drenched at 0.56 mL/kg of BW; Radix Laboratories; Eau Claire, WI; n = 6), 4) vitamin C (Vitamin C;0.56 ml/kg of BW; Radix Laboratories; Eau Claire, WI; n = 6), and 5) vitamin E (Vitamin E 300; 0.33 IU/kg of BW; Durvet Animal Health; n = 6). Growing lambs (n = 30) were also placed into the same treatment groups. Evaluation of vitamin supplementation was observed on individual time points from d 0, 14, 28, 56, and 77 from the sheep. Parameters collected include body condition score (BCS), FAMACHA score, packed cell volume (PCV), and fecal egg count (FEC). There was no effect (P &amp;gt; 0.05) on BCS in either lamb or mature groups on any of the days within the trial. However, on d 56, there was a tendency for the FAMACHA score to be improved in the vitamin E lambs compared with the control lambs. Additionally, on d 56 for the mature group, there was a significant difference (P ≤ 0.05) that was observed within the Vit E+C group being less than the Dewormer and vitamin C groups. Treatments did not affect (P &amp;gt; 0.05) packed cell volume (PCV) throughout the trial in either lamb or mature ewes. On d 14 of the trial, lambs receiving vitamin E and C, or the anthelmintic treatment had decreased (P ≤ 0.05) strongyle FEC compared with the control lambs. The preliminary data analyzed suggests that vitamin E and/or C may work similarly to pharmaceutical anthelmintics in hair sheep to combat GIN. However, more research is essential to confirm the viability that vitamins may work as a sustainable alternative.

PSI-3 Effects of a Retinoid X Receptor agonist on primary ovine satellite cells

Abstract Sheep producers are typically paid based on body weight, so understanding the mechanisms of postnatal skeletal muscle growth is vital. Satellite cells are responsible for the capacity for postnatal skeletal muscle growth. Satellite cells proliferate and then differentiate into myoblasts before fusing with existing myotubes. The retinoid X receptor (RXR) is a transcription factor that enhances myogenic differentiation 1 (MyoD) expression, which increases differentiation and fusion of myoblasts in sheep. LG 100268 is an RXR agonist, which activates the RXR. The objective of this project is to measure the effect of LG 100268 on primary ovine satellite cell (OSC) proliferation and protein synthesis rates. Primary OSC were isolated from the hind legs of 9-mo old commercial hair sheep wethers (n = 3). For proliferation, cultures were grown to approximately 70% confluency, followed by treatment with 5% fetal bovine serum (FBS) or 300 nM of LG 100268 in 5% FBS. For protein synthesis, cultures were grown to approximately 80% confluency, at which point cultures were induced to differentiate and treated 48-h later with serum free media (SFM) or 300 nM LG 100268 in SFM. Proliferation rates were measured at 24-h post-treatment, and protein synthesis rates were measured at 6-h post-treatment. Treatment with 300 nM LG 100268 increased (P = 0.004) OSC proliferation rates compared with control cultures. Preliminary protein synthesis results suggest that LG 100268 does not alter (P = 0.22) protein synthesis rates of fused OSC. However, more research is warranted to clarify the role of the RXR in sheep skeletal muscle growth.

The use of infrared thermography as an indicator of methane production in hair sheep.

Infrared thermography may be an alternative technology for measuring the amount of CH4 produced and has the advantages of low cost, speed and efficiency in obtaining results. The study's objective was to determine if the infrared thermography is adequate for predicting the emission of CH4 in hair sheep and the best time after feeding to carry out the measurement. Twelve Santa Inês lambs (females, non-pregnant, with twelve months old and mean body weight of 39.3 ± 2.1kg) remained for two days in respirometric chambers, in a semi-closed system, to determine the CH4 production. The animals were divided into two treatments, according to the diet provided. During this period, seven thermographic photographs were taken, at times - 1h, -0.5h, 0h, 0.5h, 1h, 2h, 3h, 5h, and 7h, according to the feeding time, defined as 0h. CH4 production was measured over 24h. Thermographic images measured the maximum, minimum, average and point temperatures at the left and right flanks. The temperature difference between the left and right flanks (left minus right) was calculated each time. Pearson correlation coefficients, multiple regression and principal component analysis were carried out in SAS®. The best prediction of emission intensity of CH4 (kg of CH4 per dry matter intake) was obtained at 3h after feeding: CH4/DMI = 13.9016-0,38673 * DifP2 + 3.39089 * DifMed2 (R² = 0.48), using the difference between left and right flanks for point and average temperature measures. Therefore, infrared thermography can be used as an indicator of CH4 production in hair sheep three hours after feeding.

Comparative assessment of growth curves in Brazilian white Morada Nova hair sheep breed.

The Morada Nova sheep breed is essential for the economy of the semi-arid region of Northeast Brazil, standing out for its adaptability, resistance to parasites and reproductive ability. However, the white variant is endangered, highlighting the importance of studies on its productivity to support conservation efforts. This study focuses on the growth curve of the Morada Nova sheep breed, using nonlinear models and analyzing flock profiles. Total of 764 observations of 165 animals from four farms in Ceará and Rio Grande do Norte, Brazil, were analyzed. Canonical discriminant analysis (CDA) was used for the exploratory analysis and four nonlinear models were used to study the growth curve. Weight from birth to 270days of age, absolute growth rate (AGR), and the impact of sex on growth curves were assessed. Sex and farm are significant discriminating variables (P < 0.05) for the studied effects (weight and age). Weight was the primary phenotypic biomarker that discriminated between the two indicators, while age was a discriminating indicator only for the core effect. The Gompertz model was the most efficient, presenting the lowest residuals and greatest convergence. The study reveals new information about the growth of Morada Nova sheep, the white variety, including weight differences between the sexes at all analyzed ages and an inflection point before 90days of age. These discoveries contribute to the understanding of the breed's growth and help in the formulation of conservation strategies.

Evaluation and use of recently introduced sheep breeds to Uruguay

Sheep numbers in Uruguay have declined over the last 30 years. In the north and northeast there are extensive wool and dual-purpose systems, respectively, where both wool and meat impact on income. In the south, small-scale family sheep meat production systems have flourished. In this thesis I report work pertaning to production systems in the south (1) and northeast (2) regions. Corriedale (C) is the predominant breed in the country. Milchschaf (M) has been disseminated in the south but C still prevails in the northeast. There is a paucity of rigorous evaluations of these breeds or alternatives that could be more profitable, such as Highlander (H) for the south and Dohne Merino (DM) for the northeast. I experimentally assessed: in 1), wool production, reproduction and growth in C, H and M, and in 2), wool quality and body traits in ewe hoggets from rotational crossbreeding between C and DM. In 1), wool production was better in C, but H and M outperformed C in live weight and reproductive performance. In 2), genotypes with greater proportions of DM produced lower fleece weight, and those with greater proportions of C produced coarser fibre diameter, with no differences in wool quality or morphological traits related to meat aptitude. Gross margins (GM) integrate physical performance with product values and costs, allowing monetary comparison between genotypes. I calculated GMs for a number of production and market scenarios. In 1), most often GM was greatest for H, followed by M. The differences in favor of H and M over C decreased when I considered higher feed requirements for H and M. The GM of H and M increased by assuming they were wool-less (the cost of harvesting exceeds the value of the wool produced). In 2), I considered low and high prices for wool of different fibre diameter. GM was greatest for ¾DM and ⅝DM at low prices, and for ¾DM and ½DM at high prices. C had the lowest GM in all scenarios. I recommend H for southern systems and research on hair sheep breeds. In extensive dual-purpose systems, rotational crossbreeding between C and DM allows for improved wool income without losing meat potential. I formulate recommendations about future genotype evaluations, integrating them with current within breed genetic evaluations.

98 Adding parasite resistance to the breeding objective in hair sheep

Abstract Economic selection indexes provide the best method to achieve genetic gain for multiple traits simultaneously. Hair sheep enterprises, particularly in environments with substantial gastrointestinal nematode challenge, may benefit from incorporating parasite resistance in a selection index. However, obtaining the relative economic value (REV) for parasite resistance is challenging; information on its impact on productivity is incomplete, as are the costs of treatment given anthelmintic resistance. The National Sheep Improvement Program (NSIP) currently provides producers with an index designed to increase total weight of lamb weaned per ewe lambing (TW). Our objective was to assess the effects of including fecal egg count, an indicator of parasite resistance, as an additional goal trait. Including the benchmark scenario with TW as its sole objective, 10 indexes were constructed using standard index theory. Post-weaning fecal egg count (PFEC) was added to this breeding objective with a REV of -1 and the REV for TW was varied from +1 to +5 at +0.5 increments. Weaning weight, number of lambs born and weaned, and PFEC were the selection criteria, modelled as either phenotypes or estimated breeding values (EBV). Phenotypes and EBV were simulated for 1,000 lambs by Cholesky decomposition and used to generate index scores. Ten replicates were run and the top 3% of males and 26% of females were retained on index scores. Annual responses in the goal traits were estimated. Responses in PFEC were expressed as a percentage, assuming a mean PFEC of 2,089 eggs/g as in NSIP. Concordances with those selected in the benchmark scenario were determined. Using EBV as selection criteria, TW increased by 1.7 kg/yr in the benchmark scenario (Table 1). However, unfavorably, PFEC increased by 2.3%/yr. When phenotypic criteria were used, TW increased by 0.5 kg/yr, and PFEC by 0.3%/yr. Once added to the breeding objective, PFEC decreased regardless of the REV of TW. However, response in TW also reduced, although less so as its REV increased. With EBV as the criteria, the REV of +3 for TW appeared preferable: PFEC reduced by 7.1%/yr with 98% of the response in TW retained. With phenotypic selection criteria, PFEC reduced by 5.2%/yr with 94% of the response in TW retained. With +3 REV for TW and EBV as the selection criteria, on average 65% and 82% of males and females, respectively, were chosen in common with the benchmark. When phenotypic criteria were used, those percentages were 60% and 80%, respectively. Implementing a more holistic index with REV of +3 for TW and -1 for PFEC would result in reasonable responses in both traits. However, producers will need to decide if reduced gains in TW is acceptable to improve parasite resistance in a hair sheep breeding program.

225 Genomic diversity of Katahdin sheep and impacts on genomic prediction

Abstract In the late 1950s, Katahdin hair sheep were developed as a composite breed of medium size and moderate prolificacy, with potential to express resistance to gastrointestinal nematodes. With its increasing popularity and the recent adoption of genomic prediction in the Katahdin breeding program, evaluating the genetic diversity in this breed is necessary. Prediction accuracies rely on the strength of genetic relationships. That strength often increases with selection using genomically-enhanced estimated breeding values; however, it carries the risk of decreasing diversity. We aim to characterize the genetic diversity present in the breed and the subsequent impact on the accuracies of genomic predictions. Genotypes on Katahdin sheep from member flocks in the National Sheep Improvement Program were used. Data from two medium density 50k bead chips and one high density 600k bead chip were merged and limited to shared autosomal single nucleotide polymorphisms (SNP). After quality control, there were 9,705 animals and 31,984 SNP remaining. Only for analyses of inbreeding and heterozygosity, linkage disequilibrium (LD) pruning was performed; variants with an LD score exceeding 0.8 were removed with 29,904 SNP remaining. To determine the extent of population structure, principal component (PC) analysis was conducted with PC one and PC two explaining 4.9% and 3.8% of the variation in the population, respectively. When examining subpopulations, a single ancestral population explained 99.9% of the genetic variation among animals. When clustered by identity-by-state, all animals were placed in a single cluster. Inbreeding coefficients were estimated with four methods: method of moments, variance-standardized relationship minus one, excess homozygosity, and correlation between uniting gametes. Across methods, average inbreeding coefficients ranged from 1.14% to 1.20% with Pearson and Spearman correlations ranging from -0.51 to 0.91 (Table 1). Historical effective population sizes (Ne) were estimated for earlier generations, and a linear regression fit to predict more recent Ne. At the founding of the breed, historical Ne was estimated to be 310, and the current Ne was estimated to be 150. Effects of Ne on the accuracy of genomic predictions were examined for reference population sizes ranging from 1k to 25k for traits of low (0.1), moderate (0.3), and high (0.5) heritabilities. The corresponding number of effective chromosomal segments were 2NeL, where L was the length of the genome in morgans (26M). Accuracies of genomic predictions increased as the reference population size grew, with only marginal gains once the population exceeded 15k. Overall, there were no detectable genetic subpopulations in the Katahdin breed. Current levels of inbreeding were low. With a small Ne the breed can achieve high accuracy for genomic predictions by aiming for a reference population of 15k animals. Negative impacts on genetic diversity due to genomic selection are not of immediate concern.

Genetic variation in two candidate genes against gastrointestinal parasites in Colombian Hair Sheep

Objective. To characterize two SNP-type genetic polymorphisms in the GLI1 (rs411868094) and IL20RA (rs419463995) genes, candidates for resistance against gastrointestinal parasites in two biotypes of Colombian hair sheep. Materials and methods. From the DNA bank of the Animal Genetics Laboratory of the University of Sucre, 167 samples, belonging to the Ethiopian (n=94) and Sudan (n=73) biotypes, were analyzed by PCR and subsequent bidirectional sequencing of two SNPs in the GLI1 (T&gt;G) and IL20RA (G&gt;A) genes. Allelic and genotypic frequencies, observed (Ho) and expected (He) heterozygosity, F index, and Hardy-Weinberg equilibrium deviations (EHW) were calculated using the GENALEX version 6.5 program. Results. For the GLI1 locus, the mean genotypic frequencies were 0.155±0.07, 0.370±0.07, and 0.475±0.07 for GG, GT, and TT, respectively. In the Ethiopian biotype, the highest frequencies of the genotype of interest (GG) were found. For the IL20RA locus, the AA and AG genotypes had similar and the highest frequency (0.465±0.03) compared to the GG genotype (0.110±0.01). The genotype of interest at this locus (AA) was the most frequent in both OPC biotypes. Conclusions. The alleles of interest associated with low FEC had a low frequency for the GLI1 gene, but a high frequency for IL20RA. The Ethiopian OPC biotype showed the highest frequencies of the genotypes of interest.

Estimation of the growth curve in Colombian sheep using the Richards model

Objective. To describe growth in Colombian hair sheep (OPC) using the Richards model. Materials and methods. A total of 2086 records were obtained from weighing every 30 days in OPC sheep from birth to slaughter and weaning at 90 days. In addition, the sex (S), type of lambing (TP) and time of birth (Eponac) of the animals were considered. The data were analyzed with the Richards model using the NLIN procedure of SAS. Results. The asymptotic weight estimation indicated by parameter A for males was 7.8 kg higher than that of females; in the TP, this same parameter indicated a 22% superiority between single and multiple births; finally, in the Eponac variable, the best weight values corresponded to the rainy season with 5 kg more than the animals born in the dry season. For the K parameter, the reference values oscillate between 0.001 and 0.004 in the variables S, TP and Eponac; as well as the correlation between the A and K parameters, the values are between -0.98 and -0.99 in all the variables studied. Conclusions. The Richards model explained the development of the animals and allowed observing the effect of the variables S, TP and Eponac, evidencing in each of these a slow growth, but with high weights at maturity.

Impact of Agro-Byproduct Supplementation on Carcass Traits and Meat Quality of Hair Sheep and Wool × Hair Crossbreds Grazing on Fescue Pasture.

The effects of breed type (purebred or crossbred) and supplementation of agro-byproducts on the growth, carcass characteristics, and meat quality of landrace hair (Barbados Blackbelly; BB and St. Croix; SX) lambs was evaluated. Thirty-six 7.5-month-old purebred hair (BB and SX; body weight = 24.1 ± 4.26 kg) and terminal sire (Dorset; DO) crossbred lambs (DO × BB and DO × SX; body weight = 31.4 ± 3.50 kg) rotationally grazed predominantly on Jesup tall fescue pasture during spring with or without agro-byproduct supplementation (soyhull or corn gluten feed at 2% of BW). Following a 77d grazing period, the lambs were harvested, and their carcass characteristics and meat composition were evaluated. Both supplementation and crossbreeding significantly increased their carcass weight and primal cuts, whereas only supplementation increased (p < 0.01) the dressing percentage, and crossbreeding increased the shear force (p < 0.01). Regardless of breed type, supplementing agro-byproducts improved the lipid oxidation stability and texture properties of the fresh lamb, whereas the pasture-only lambs had healthier fatty acid profiles compared with the supplemented lambs. The results indicate that both terminal sire crossbreeding and byproduct supplementation can be used to affect the carcass characteristics and meat composition of landrace hair sheep lambs.

Effect of Brosimum alicastrum Foliage on Intake, Kinetics of Fermentation and Passage and Microbial N Supply in Sheep Fed Megathyrsus maximus Hay.

An experiment was carried out to assess the effect of the incorporation of sun-dried foliage of Brosimum alicastrum into rations based on hay of Megathyrsus maximus on intake, rumen fermentation, kinetics of passage, microbial nitrogen supply to the small intestine, apparent digestibility in Pelibuey hair sheep. Four rations were randomly allotted to four rumen-cannulated lambs (BW = 37.4 ± 4.9 kg) using a 4 × 4 Latin square design to assess the effect of increasing levels (0, 15, 30 and 45% DM basis) of foliage of Brosimum alicastrum on a basal ration of M. maximus. Organic matter intake and water consumption increased linearly (p < 0.01) with increasing levels of B. alicastrum in the ration. The rate and potential extent of rumen fermentation of OM and CP of B. alicastrum were 10.6%/h and 86.6% and 11.4%/h and 95.2%, respectively, but no effect (p > 0.05) was found on the potential rumen degradation of DM (40.2%) or on the rate of degradation of DM (0.033%/h) of M. maximus, although a positive effect was found in the rumen degradation rate of NDF (p < 0.05). VFA and ammonia concentration in the rumen and the rate of passage of solids and liquids through the rumen (k1) increased linearly (p < 0.01) with increasing levels of B. alicastrum. Rumen pH was not affected by the incorporation of B. alicastrum (p > 0.05). Microbial nitrogen supply to the small intestine (p < 0.001), apparent digestibility of dry matter (p < 0.01) and NDF (p < 0.05) of the rations were also significantly increased as a result of the incorporation of B. alicastrum foliage. Results from this experiment suggest that the foliage of Brosimum alicastrum can be readily incorporated at around 30% of the ration of dry matter in hair sheep with beneficial effects on feed intake, rate of passage and microbial N supply to the lower tract.

Reproductive and productive performance of hair sheep in a semi-intensive system in southeastern Mexico

Productivity measured as kilograms of lamb weaned per ewe is a composite trait of economic importance and can be used as selection criterion of maternal breeds. The objective of this study was to estimate the reproductive, preweaning growth and productivity performance of hair breed ewes, and the effect some nongenetic factors influencing them under semi-intensive conditions in southeastern, Mexico. Information of purebreds and crossbred ewes and their lambs was used to develop a composite productivity index. The final mixed model used (except for age at first lambing, AFL), included the fixed effect of breed group, year (Y, 2016-2019) and season of lambing (dry, rainy and wind and rainy), lambing number (1, 2, … ≥ 5), litter size (LS, single and double for weaning traits), and the random effects of ewe within breed group and residual error. Except for the AFL, the effect of the breed group and all other non-genetic factors were significant (P &lt; 0.0100). No breed or crossbred was superior for all traits studied, yet Katahdin breed (K) excelled the most, despite of its reproductive performance. Traits in the productivity index (litter size at lambing, adjusted litter weaning weight and lambing interval) could not be used as an optimal indicator for the identification of the best breed for crossbreeding. The K showed the best maternal ability, except for lambing interval and AFL, influenced by all non-genetic factors which could be improved by sound flock management.

73 Deworming to improve growth in early-weaned spring born hair sheep lambs

Abstract In lambs, the stress of weaning and the lack of a fully developed immune system can increase susceptibility to gastrointestinal nematodes (GIN). Lack of an effective GIN control strategy around this time can have a significant impact on lamb growth, productivity and mortality. The objective of this study was to determine the influence of deworming at weaning on growth performance in hair sheep lambs. St. Croix (STX) and Barbados Blackbelly (BB) lambs used in the study were born on pasture, weaned at 60.2 ± 0.4 d of age, and transitioned in pens for 87 d post-weaning before turning out to pasture. After accounting for initial FAMACHA eyelid color score, breed, and birth type (single or multiple) at weaning, 54 STX (n = 32) and BB (n = 22) lambs weighing 11.7 ± 0.4 kg were dewormed (DEW) or not (CON) with a combination of levamisol (Prohibit; 8 mg/kg BW) moxidectin (Cydectin; 0.2 mg/kg BW) and albendazole (Valbazen; 7.5 mg/kg BW). To evaluate the effect of deworming treatment, BW and body condition scores (BCS; scale 1-5) were recorded at weaning and at end of transition to pasture. Blood and fecal samples were also collected for determination of packed cell volume (PCV) and fecal egg counts (FEC). Pooled treatment group feces (d 0 – 98) were collected and cultured to determine GIN genera at weaning. Data were analyzed using repeated measures in a mixed model, and FEC were log transformed prior to analysis. There was a mixed population of GIN at weaning averaging 65% and 35% for H. contortus and Tricostrongylus spp. At weaning, BCS, PCV, and FEC were similar between treatment groups and averaged 1.6 ± 0.07, 36.5 ± 0.6%, and 399 ± 54.4 epg, respectively. Combination deworming reduced FEC by 99%. At turnout, DEW lambs (2.3 ± 0.1) tended (P = 0.08) to have greater BCS than CON lambs (2.0 ± 0.1) and PCV was greater (P &amp;lt; 0.001) in DEW versus CON lambs (37.2 ± 0.9 and 33.3 ± 0.8%, respectively). There was also a tendency (P = 0.09) for breed to influence BCS (2.3 ± 0.1 and 2.0 ± 0.1 for BB and STX, respectively). The FEC at turnout was not influenced by treatment or breed (496.7 ± 75.1 epg). Additionally, DEW lambs (131.8 ± 5.2) tended (P = 0.09) to grow faster than CON (119.9 ± 4.7 g/d) lambs, a difference more pronounced in STX DEW (g/d) than STX CON lambs (136 ± 6.1 vs 110 ± 6.5 g/d; P &amp;lt; 0.05). Even though deworming tended to promote faster growth rates in lambs used in this study, alternative, more sustainable, parasite control strategies should be considered in the wake of increasing dewormer resistance.

117 Supplementation with soy hull during late gestation and lactation on parasite indicators in hair sheep ewes

Abstract Before lambing and up to 8 wk during lactation, ewes experience a temporary loss of immunity to gastrointestinal nematodes (GIN). This can result in a periparturient increase in fecal egg counts (FEC) along with clinical symptoms of parasitism. This increase in FEC can lead to greater larval numbers on pasture, consequently exposing lambs to a greater level of infection that can impair production. Adequate supplementation during late gestation and lactation has been shown to reduce the impact of this temporary loss in immunity and decrease GIN infection levels in ewes. This study evaluated the supplementation of an agro-byproduct (soy hull) on GIN infection parameters in hair sheep ewes. Pregnant ewes (n = 36) were allocated, balanced by breed, parity and fetal numbers to either corn/soybean (CS) or soy hull (SH) supplementation during the last trimester of pregnancy. Ewes rotationally grazed predominantly fescue pastures subdivided into 6 sections (0.13 ha) using electro-netting (3 sections of 6 ewes/supplement type). Ewes were supplemented at either 0.75% BW (late gestation) or 1.5% BW (lactation) using a single feeder per section. Ewes lambed on pasture and lambs were weaned at approximately 63 d. Lambs had access to the supplement provided to their dams. Blood and fecal samples were collected in prepartum, postpartum and at weaning for determination of packed cell volume (PCV) and FEC. Pooled treatment group feces were also collected and cultured to determine GIN genera. Body condition scores (BCS) were also recorded at each sampling. Data were analyzed in a model with supplement type and breed as the main effects and FEC were log transformed before analysis. There was a mixed population of GIN throughout the study with H. contortus (49.5%) and Tricostrongylus spp. (46.6%) being the most common. Supplement type had no effect on ewe BCS prepartum, postpartum or at weaning (averaging 2.6 ± 0.1, 2.3 ± 0.1 and 2.0 ± 0.1, respectively). Supplement type influenced PCV at weaning only, with ewes supplemented with CS having a greater (P &amp;lt; 0.03) PCV than those supplemented with SH (33.0 ± 0.7% and 30.8 ± 0.7%, respectively). PCV was similar between treatments prepartum (38.4 ± 1.3%) and postpartum (34.4 ± 0.9%). Ewe FEC was similar between CS and SH supplemented ewes prepartum (271.6 ± 0.5 epg) and at weaning (298.5 ± 80.5 epg); however, at postpartum sampling CS ewes tended (P = 0.09) to have reduced FEC (234.1 ± 62.0 epg) compared with SH (414.1 ± 59.6 epg) supplemented ewes. At weaning, lamb FEC was not influenced by supplementation or breed and averaged 502.3 ± 83.2 epg. Data indicate that substituting SH for a more traditional corn-based supplement in landrace hair sheep ewes managed in a pasture-based system had no influence on GIN infection. Agro-byproduct supplementation should be explored further for their use in sustainable, forage-based sheep production systems.

46 Use of soy hull as a supplement during late gestation and lactation for landrace hair sheep ewes in a forage-based system

Abstract Forage-based production systems can be limiting in providing adequate nutrition as the result of seasonal fluctuations in forage quality and quantity, especially during periods of increased nutritional demands such as late gestation and lactation. This study evaluated the use of an agro-byproduct supplementation (soy hull) to fill these demands. Barbados Blackbelly (BB) and St. Croix (STX) hair sheep ewes were bred November 1 in a 25-d breeding season in two single-sire groups to like breed sires, and initially managed as one group. Pregnant ewes (n = 36) were allocated, balanced by breed, parity and fetal numbers to either a corn/soybean (CS) or soy hull (SH) supplementation starting the last trimester of pregnancy. Ewes rotationally grazed predominantly fescue pastures subdivided into 6 sections (0.13 ha) using electro-netting (3 sections of 6 ewes per supplement type). Ewes were supplemented at either 0.75% BW (late gestation) or 1.5% BW (lactation) using a single group feeder per section. Ewes lambed on pasture and lambs were weaned at approximately 63 d. Lambs had access to the supplement provided to their dams. Data were collected on ewe BW changes and reproductive performance, and analyzed in a model with supplement type and breed as main effects. Results are presented as LSM. Supplement type had no effect on ewe prepartum (54.7 kg), postpartum (47.3 kg) and weaning BW (44.7 kg), whereas BW was consistently heavier in STX than BB ewes. Ewe late gestation (61 g/d) and lactation ADG (-51 g/d) were not affected by supplement type though breeds differed (P &amp;lt; 0.01) in lactation ADG (BB: -14 vs STX: -78 g/d). Lambing performance was also not affected by supplement type with 1.97 lambs born live, and 1.69 lambs weaned per ewe. There was a supplement type by breed interaction (P &amp;lt; 0.05) for number of lambs weaned with STX ewes receiving SH having a larger litter size at weaning than ewes receiving CS (1.40 vs. 2.10 lambs per ewe) with no difference in BB ewes (1.71 vs. 1.50 lambs per ewe, respectively). Neither litter birth (6.14 kg) and weaning weights (19.9 kg) nor litter ADG (233 g/d) were affected by supplement type. Litter BW was significantly greater (P &amp;lt; 0.01) in STX than BB (6.85 vs 5.18 kg), but not different at weaning. Lamb birth and weaning weights were not affected by supplement type, though preweaning ADG tended (P &amp;lt; 0.1) to be greater in CS than SH (162 vs. 142 g/d). Data indicate that substituting SH for a more traditional corn-based supplement in landrace hair sheep ewes managed in a pasture-based system did not affect ewe growth, reproductive performance, and lamb performance. Agro-byproduct supplementation should be explored further for use in sustainable, forage-based sheep production systems.

114 The efficacy of a natural fungus (Duddingtonia flagrans) in reducing gastrointestinal nematode indicators in lambs

Abstract Sustainable and profitable small ruminant production in the US is affected by infections with gastrointestinal nematodes (GIN), especially the blood sucking GIN, Haemonchus contortus. The overuse and misuse of available drug classes has led to multi-drug resistant GIN that pose significant challenges to parasite control on many farms. The objective of this study was to evaluate the effectiveness of a natural fungus (Duddingtonia flagrans; Bioworma, International Animal Health) in reducing GIN larval counts and other GIN indicators in hair sheep wethers. Eighteen St. Croix (n = 9) and Barbados Blackbelly (n = 9) wethers (227 ± 1.4 days of age and 29.7 ± 0.6 kg BW) were dewormed (d 0) with a combination of levamisol (Prohibit; 8 mg/kg BW) moxidectin (Cydectin; 0.2 mg/kg BW) and albendazole (Valbazen; 7.5 mg/kg BW) prior to the start of feeding according to the manufacturer’s recommendations for feeding BioWorma. At this time, lambs were separated into two treatment groups (n = 9/group), split into 3 replications per treatment group and placed on six pasture paddocks (0.06 ha; n = 3 per paddock) after accounting for breed, initial fecal egg count (FEC) and BW. Lambs were then fed daily either a grain supplement ration (corn and soybean meal) with Livamol with Bioworma (LIV) or without (CON) at 2% of their BW for 98 d. LIV was added to the ration based on total lamb BW/paddock. To evaluate the effect of LIV treatment, BW and body condition scores (BCS) were recorded every 2 wk for 98 d. Blood and fecal samples were also collected for determination of packed cell volume (PCV) and FEC. Pooled treatment group feces (d 0 – 98) were collected and cultured to determine GIN genera. A subset of animals/treatment (n = 3) will be harvested to determine abomasal worm counts. Data were analyzed using repeated measures in a mixed model, and FEC were log transformed before analysis. Following deworming (d 0), FEC were reduced by 100% by d 14. There was a mixed population of GIN at the start of the study (averaging 54%, 42%, 1.2% and 1.8% for H. contortus, Tricostrongylus spp., Oesphagostomum spp. and Nematodirus spp., respectively). LIV with Bioworma supplementation had no impact on BW, BCS, PCV or FEC in this study averaging 34.2 ± 0.3 kg, 2.5 ± 0.04, 34.7 ± 0.5% and 150.9 eggs per gram, respectively. Under the conditions of this study, Bioworma® supplementation had no influence on GIN indicators measured up to 100 d of grazing. This research will be continued during subsequent grazing seasons to determine the effect of continued supplementation on lamb parasite load and performance as well as pasture infestation levels.

Reproductive and productive behavior of hair sheep under an intensive production system

Objective: To evaluate the reproductive and productive behavior of four hair sheep breeds in an intensive production system.&#x0D; Design/Methodology/Approach: Data recorded over 4 years (2016-2019) from a production unit that works with Blackbelly, Pelibuey, Dorper, and Katahdin breeds were analyzed. The following variables were evaluated: fertility, prolificacy, birth weight (BW), weaning weight (WW), weaned lamb yield (WLY), daily weight gain during lactation (DWGL), offspring born alive (OBA), male offspring (MO), and female offspring (FO). All information was analyzed using Chi-square tests and analysis of variance.&#x0D; Results: The fertility, BW, WW, and WYL variables recorded different values between breeds (P&lt;0.05). The greatest fertility and prolificacy were recorded by Blackbelly, while Dorper recorded the lowest values (P&lt;0.05). BW and WW were highest in Dorper and lowest in Blackbelly (P&lt;0.05). Finally, the sheep that recorded the highest WYL were the Blackbelly, while the Dorper registered the lowest values (P&lt;0.05). BW and DWGL values reached maximum values (P&lt;0.05) in Dorper rams, followed by Katahdin. The greatest number of OBA was observed in Blackbelly and Pelibuey (P&lt;0.05).&#x0D; Study Limitations/Implications: Further studies should be carried out to validate this research.&#x0D; Findings/Conclusions: Blackbelly ewes produced more kilograms of weaned lambs per lambing ewe. The Dorper and Katahdin rams in the pre-weaning period recorded higher weight at weaning.

Production and quality of meat from hair sheep grazing on Tanzania grass and supplemented with different protein levels

Objective: To evaluate the effect of a supplementary feeding (with different crude protein (CP) levels) in the yield and growth performance and meat characteristics of hair lambs grazed on Tanzania grass.&#x0D; Design/Methodology/Approach: A 120-d-1 experiment was conducted; it included four treatments and seven replications in a completely randomized design. Twenty-eight hair lambs (22.6 ± 1.6 kg LW) were allowed to graze on Tanzania grass (Panicum maximum) and were provided concentrate feeds (with 10, 12, 14, and 16% crude protein). The aim was to assess the effects of the latter food on growth, carcass characteristics, and meat quality.&#x0D; Results: Compared with the lambs fed with 10, 12, and 14% CP, the heaviest carcasses (P&lt;0.05) were obtained from lambs fed with 16% CP. The percentage of crude protein and fat of the biceps femoris linearly increased (P&lt;0.05) as the CP percentage increased in the concentrate feed. Meat color, water retention capacity, and cutting force were not impacted by the CP percentage of the concentrate feeds. Compared with the lambs fed with 10, 12, and 14%, the lowest palmitic acid percentage and the highest oleic acid percentage were found in the meat of lambs fed with 16% CP.&#x0D; Study Limitations/Implications: A high area was selected to avoid excessive rain.&#x0D; Findings/Conclusions: Compared with the lambs fed with 10, 12, and 14% CP, the lambs grazed on Tanzania grass and supplemented with 16% CP grew more, recorded a higher carcass yield, and their meat had a better unsaturated fatty acids ratio.