PSXIV-19 Heritability for growth and resistance to gastrointestinal parasitism in meat goats and hair sheep

Genetic selection for resistance to internal parasitism is of great research interest. Heritabilities were determined for average daily gain (ADG), logarithmic transformed fecal egg count (FEC), packed cell volume (PCV), and serum immunoglobin (Ig) levels of growing male meat goats and hair sheep from different farms in the southcentral USA during three consecutive central performance tests (CPT). Tests entailed 7–10 wk of data collection after artificial infection with Haemonchus contortus. In year 1, animals evaluated were selected randomly and in years 2 and 3 progeny of CPT sires classified as highly or moderately resistant, which included 46, 50, and 51 Boer, Kiko, and Spanish and 59, 61, 34, and 46 Dorper, Katahdin-farm A, Katahdin-farm B, and St. Croix, respectively. Females were classified accordingly on-farm based on FEC and FAMACHA. Pedigree records consisted of 32 and 57 known sires, 95 and 152 known dams including 4 and 10 full-sibs and 97 and 149 half-sibs for goats and sheep, respectively. Variance components and heritabilities were estimated by AIREML using WOMBAT with a multivariate animal model. Heritability estimates were 0.48 ± 0.214 and 0.85 ± 0.157 of ADG, 0.31 ± 0.237 and 0.20 ± 0.172 of FEC, 0.60 ± 0.206 and 0.24 ± 0.185 of PCV, 0.26 ± 0.172 and 0.51 ± 0.167 of IgA, 0.335 and 0.543 of IgM, and 0.14 ± 0.192 and 0.31 ± 0.190 of IgG for goats and sheep, respectively. Reasons for relatively high heritabilities for all traits include the low residual variance estimates due primarily to a standardized environment in the performance test. In conclusion, moderate to high heritabilities were found for growth performance and response to parasite infection for growing meat goat and hair sheep males under a standardized environment that suggests considerable for genetic improvement through selection.

PSXIV-18 Genetic improvement for resistance to gastrointestinal parasitism in growing meat goats and hair sheep through a centralized performance test in the southcentral USA

Progress from selecting meat goats and hair sheep from different farms in the southcentral United States for resistance to internal parasitism during three consecutive central performance tests was evaluated. Tests entailed 7–10 wk of data collection after artificial infection of growing males with Haemonchus contortus larvae. There were 44, 50, and 50 Boer, Kiko, and Spanish goats and 54, 55, 34, and 47 Dorper, Katahdin-farm-A, Katahdin-farm-B, and St. Croix sheep, respectively. In year 1, males were randomly selected and in years 2 and 3 were progeny of sires and females classified as highly and moderately resistant. Criteria for males was average daily gain and residual feed intake during the performance test and means of fecal egg count (FEC) and packed cell volume after artificial infection and for females was FEC and FAMACHA on-farm. There were interactions in FEC of breed×year (P < 0.001) for both species (1,046; 1,134; and 2,630 for Boer; 3,781; 1,239; and 1,216 for Kiko; 1,303; 1,357; and 1,464 for Spanish; 3,288; 1,956; and 1,315 for Dorper; 1,528; 1,759; and 2,241 for Katahdin-A, 2,414; 3,874; and 1,793 for Katahdin-B; and 1,371; 1,160; and 1,175 eggs/g for St. Croix in years 1, 2, and 3, respectively) and year×resistance group (RG; P = 0.005) for goats (1,359; 610, and 552 for high; 1,951; 1,268; and 1,440 for moderate; 2,821; 1,852; and 3,118 eggs/g for low RG in years 1, 2, and 3, respectively) but not for sheep (P = 0.639). In conclusion, resistance appeared greatest for Spanish and St. Croix within species and was increased by selection of Kiko and Dorper. For highly resistant goats, lower FEC in year 2 and 3 vs. 1, compared with no year differences for moderate and low RG, indicates selection progress, and the lack of similar differences for sheep may reflect their relatively greater resistance.

PSXII-30 Genetic and phenotypic correlations for growth and resistance to gastrointestinal parasitism in meat goats and hair sheep

Genetic and phenotypic correlations for growth and response to parasite infection traits were estimated for growing male meat goats and hair sheep from different farms in the southcentral United States during three consecutive central performance tests (CPT). Data were collected for 7–10 wk after artificial infection with Haemonchus contortus, which included average daily gain (ADG), fecal egg count (FEC), packed cell volume (PCV), and immunoglobin (Ig) levels. Animals evaluated were selected randomly in year 1 and in years 2 and 3 progeny of CPT sires classified as highly or moderately resistant and included 46, 50, and 51 Boer, Kiko, and Spanish goats and 59, 61, 34, and 46 Dorper, Katahdin-farm A, Katahdin-farm B, and St. Croix sheep, respectively. Females were classified accordingly on-farm based on FEC and FAMACHA. Pedigree records included 4 and 10 full-sibs and 97 and 149 half-sibs for goats and sheep, respectively. Variance components and correlations were estimated by AIREML using WOMBAT with a multivariate animal model. The additive genetic correlation between FEC and PCV was negative for goats (r=-041, P < 0.001) but positive for sheep (r=0.21, P = 0.004), whereas the phenotypic correlation between FEC and PCV was nonsignificant for goats but negative for sheep (r=-0.252, P < 0.001). The genetic correlation between FEC and IgA was positive (r=0.39, P < 0.001) for goats but nonsignificant (P = 0.439) for sheep, whereas those of FEC with IgM and IgG were both negative (r=-0.369 and -0.732 with IgM and r=-0.284 and -0.702 for goats and sheep, respectively; P < 0.001). Genetic and phenotypic correlations between ADG and FEC were nonsignificant for both species. In conclusion, different relationships of FEC and PCV between species require careful attention during selection and the lack of relationship between ADG and FEC suggests that selection of growing male meat goats and hair sheep for resistance to internal parasitism will not adversely affect growth performance.

PSXI-28 Effect of pre-slaughter transport stress on carcass weight, rumen fermentation and bacterial community of growing goats

This study evaluated the effects of pre-slaughter transport stress on the rumen fermentation and bacterial community of growing meat goats. Fifty-four male Spanish growing meat goats (28.9 ± 4.5) were stratified by body weight and randomly assigned into three treatment groups (n = 18 per treatment; 1) No transport stress (CON), 2) Transport stress for 30 mins (LS), and 3) Transport stress for 3 h (HS). Blood samples were collected before and after transport to estimate plasma cortisol concentrations. At the end of the experiment, the goats were slaughtered to determine the carcass weight and to collect rumen ruminal content for pH, 16 sRNA gene sequencing, and volatile fatty acid profile. The Linear discriminant analysis (LDA) effect size and the functional profiling software (PICRUst) were used to estimate the differentially abundant taxa and predicted the functional potential of the microbial community, respectively. Compared to CON, both LS and HS increased (P < 0.01) plasma cortisol concentrations (27.5 vs. 130.1 and 117.7 ng/ mL), no differences were observed in hot carcass weight and VFA profile (P > 0.05). Rumen pH was lower (P < 0.05) in HS compared to CON or LS (6.44 vs 6.75 or 6.77). Compared to CON, LS reduced the relative abundance of Ruminococcaceae UCG 014 (LDA = 4.20; P = 0.01), whereas no effect was observed for HS. Compared to CON, predicted microbial functions associated with the immune system, translation, and enzyme activities were downregulated by LS while that of energy metabolism was downregulated by HS. Compared to HS, the predicted microbial functions associated with immune and digestive systems were downregulated by LS. This study demonstrated that LS transport stress has a more pronounced effect than long-term exposure on the rumen bacterial community and predicted functional potential in growing meat goats.

Genetic Selection for Resistance to Gastrointestinal Parasitism in Meat Goats and Hair Sheep through a Performance Test with Artificial Infection of Haemonchus contortus

Internal parasitism has been the leading cause of morbidity and mortality in small ruminants in many areas such as the southcentral USA. Among the different approaches and management practices to cope with internal parasitism, genetic selection for internal parasite resistance is recognized as one with considerable potential long-term impact. A central performance test with artificial infection of Haemonchus contortus for selection of growing meat goats and hair sheep for breeding to increase resistance to internal parasitism and on-farm selection of females was conducted for 3 years. The results varied considerably among breeds of goats and flocks of sheep. Spanish goats and St. Croix sheep maintained relatively low fecal egg count (FEC) each year, whereas for goats categorized as being of high resistance and Dorper sheep FEC decreased with advancing year. Packed call volume (PCV) and total serum immunoglobulin (Ig) levels were not strongly related to FEC. Genetic parameters varied between the two species, which might be related to previous selection pressure exerted for parasite resistance. Heritability of FEC was higher in goats than sheep. The genetic correlation between FEC and IgM and IgG was negative for both species, which suggests possible genetic association. Genetic and phenotypic correlations between ADG and FEC were nonsignificant for both species. In conclusion, different relationships of FEC and PCV between species require careful attention during selection and the lack of relationship between ADG and FEC suggests that selection of growing male meat goats and hair sheep for resistance to internal parasitism will not adversely affect growth performance.

Prevalence, genetic characterization, and antimicrobial resistance of Salmonella isolated from meat goats in the Northeastern region of Thailand

This study aimed to determine the prevalence, genotypic diversity, and antimicrobial resistance pattern of Salmonella isolated from meat goats in the Northeastern region of Thailand. A total of 1,014 rectal swabs were collected from 30 meat goat farms during April to November, 2018. Salmonella was isolated and identified according to the International Organization for Standardization protocol (ISO-6579:2002/AMD:2017) and serotyped using a slide agglutination test following the Kauffmann-White scheme. An antimicrobial susceptibility test to determine minimal inhibitory concentration (MIC) of 12 antimicrobial agents was performed using a broth microdilution method following the CLSI protocol (2017). Pulsed-field gel electrophoresis (PFGE) of XbaI digested chromosomal DNA was used to determine genotypic diversity of the isolates. The overall prevalence of Salmonella in the meat goats was 1.28%. A total of 13 Salmonella isolates recovered from the meat goats belonged to 4 serovars includings. Weltevreden (n=4), S. Bovismorbificans (n=4), S. Paratyphi B (n=4), and S. Stanley (n=1). Antimicrobial susceptibility testing revealed 2 antibiogram patternS. Eleven Salmonella isolates were susceptible to all antimicrobial agents tested, except sulfamethoxazole, and the other 2 isolates were susceptible to all antimicrobials. Genetic characterization of 13 Salmonella isolates by PFGE revealed 9 PFGE patterns that were grouped into 4 major clusters, A, B, C and D, with an 80% similarity value. This study revealed a low prevalence of Salmonella in meat goats in the Northeastern region of Thailand. Salmonella isolates were susceptible to most antimicrobials tested, with a very high proportion of resistance to sulfamethoxazole being observed.

Body Condition Score for Monitoring the Performance and Health of Small Ruminants in Field Conditions

Frequent inspection and provision for necessary care are of prime importance for sustainable production and improving the wellbeing of small ruminants. Most small-ruminant farmers are small-scale, with limited resources, and do not have facilities needed for routine evaluation and intensive care of animals. The identification of a predictive variable of animal health and wellbeing would be useful for small ruminant management in field conditions. The objective of this study was to assess the relation of body condition score to other health parameters in meat goats and hair sheep. Performance data (live weight, body condition score (BCS – 1–5: 1- very thin, 5 - obese), and FAMACHA (a 5-color chart used to monitor anemic condition in small ruminants caused by barber pole worm; score - 1–5: 1–2- not anemic, 5 - extremely anemic) of meat goats (Kiko) and hair sheep (Katahdin and Katahdin-St. Croix cross) were collected from different grazing studies conducted from 2015 to 2020 (15) and similar data plus hoof condition (1–3: 1-good, no trimming required; 2 – trimming required; 3 – trimming and additional care required) collected from farmers’ field (6; animals in a herd/flock ranged from 15 to 65) in 2020 were used in this study. Data from each study and for each animal species were analyzed separately for correlation among the performance variables in SAS 9.4, with alpha value set at 0.05. Except for few data sets, correlations between BCS and FAMACHA were negative and significant (P < 0.05) with correlation coefficient (r) ranging from -0.18 to -0.64. BCS was positively correlated with live weight (P < 0.05, r = 0.15–0.76) in most of the studies. In one study, which also included fecal egg count for the quantification of gastrointestinal parasites along with other animal performance variables, BCS was negatively correlated with the total fecal egg count (P < 0.0001, r=-0.38). BCS showed negative correlation with hoof score in goats (P < 0.001, r=-0.33). Results show that BCS can be used as a predictor for small-ruminant health, especially in field conditions where other evaluation methods are not available.

Carcass Traits of Growing Meat Goats Fed Different Levels of Hempseed Meal

Industrial hemp is currently being investigated as a potential new crop in the U.S. with the 2014 and 2018 Farm Bills passage. Hemp seeds are utilized to produce hemp oil and result in Hempseed Meal (HSM) production, rich in crude protein and fiber, making it an ideal candidate as a feedstuff for ruminant animals. This study evaluated the effects of feeding different levels of HSM on the carcass traits and meat quality of crossbred Boer goats. Forty castrated male goat kids with an initial average body weight of 25.63±.33 kg and approximately six months of age and kg were assigned to one of four treatments (n = 10) in a completely randomized design. Goats were fed pelleted diets (50% forage and 50% concentrate). Treatments consisted of different levels of HSM: control with 0%, 10%, 20%, and 30% HSM supplementation of the total diets. The goats were harvested, and carcasses were processed at the Lambert-Powell Meat Laboratory at Auburn University after a 60-d feeding trial. Data were analyzed using the GLIMMIX procedures of SAS 9.4 (SAS Inst. Inc., Cary, NC). There were no significant differences (P > 0.05) on the mean values of dressing percentages (46.59, 45.42, 45.77, and 46.16% for 0, 10, 20 and 30% HSM, respectively) and ribeye area (3.68, 3.4, 3.47, 3.39 inches, respectively). The percentage of moisture, fats, proteins, and collagen in the muscles showed no significant difference (P > 0.05) between the different levels of HSM-containing diets. The marbling scores (376, 399, 355, 364 respectively) were also not significantly different (P > 0.05) among the treatments and are representative of marbling scores indicative of “slight.” Results suggest that producers can include up to 30% of HSM in the diets of growing meat goats without creating a detrimental effect on carcass traits.