Thermoregulatory response of Yankasa sheep with distinct thick-coarse and shortslick hair types during hot-dry season in tropical Savannah

The skin has the closest contact with the environment and, thus, the role of coat in the adaptation to the changing environmental conditions cannot be over emphasised. The study was aimed at comparing the thermoregulatory response of Yankasa rams with distinct thick coarse and short-slick hair types at the peak of the hot-dry season in tropical Guinea Savannah. A total of 10 Yankasa rams with thick-coarse (n=5) and short-slick (n=5) hair types, balanced for age and body condition score were used. The meteorological and thermoregulatory parameters were measured four times at 2 days interval at 9:00, 13:00 and 17:00 h. In the afternoon, the temperature humidity index and ambient temperature were higher than the thermoneutral zone for sheep. Yankasa sheep with thick-coarse hair had higher (P < 0.05) hair length than those with short-slick hair type. Respiratory rate at all hours, body surface temperature in the morning hours, eye and inter-digital surface temperature in the afternoon hours were lower in thick-coarse hair than short-slick hair sheep. Significant rise (P < 0.05) in respiratory rate, skin and rectal temperatures from morning to afternoon hours were observed in both hair types. Subsequently, in the evening hours, the rectal temperature in the thick-coarse hair sheep returned to values comparable to those of the morning hours; while the values in short-slick hair sheep remained higher (P <0.05) than that of the morning hours. It was concluded that Yankasa sheep with thick-coarse hair type had lower thermoregulatory demand to maintain homeostasis in the afternoon hours, and cooled faster in the evening hours relative to their short-slick hair type counterpart during the hot-dry season in the tropical Savannah. La peau a le contact le plus facile avec l'environnement et, par conséquent, le rôle du pelage dans l'adaptation aux conditions environnementales changeantes ne peut pas être trop souligné. L'étude visait à comparer la réponse thermorégulatrice des béliers yankasa avec des types distincts de cheveux épais-grossiers et courts au plus fort de la saison chaude et sèche dans la savane tropicale de Guinée. Un total de 10 béliers Yankasa avec des types de cheveux épais-grossiers (n=5) et short-slick (n=5), équilibrés pour l'âge et le score d'état corporel ont été utilisés. Les paramètres météorologiques et thermorégulateurs ont été mesurés quatre fois à intervalles de 2 jours à 9 h, 13 h et 17 h. Dans l'après-midi, l'indice d'humidité de la température et la température ambiante étaient plus élevés que la zone thermonéutrale pour les moutons. Les moutons Yankasa aux cheveux épais et grossiers avaient une longueur de cheveux plus élevée (P < 0.05) que ceux de type cheveux courts. La fréquence respiratoire à toute heure, la température de surface du corps le matin, la température des yeux et de la surface inter-numérique dans les heures de l'après-midi étaient plus faibles dans les cheveux épais-grossiers que les moutons cheveux courts lisses. Des hausses significatives (P < 0.05) des températures respiratoires, cutanées et rectales du matin à l'après-midi ont été observées dans les deux types de cheveux. Par la suite, le soir, la température rectale chez les moutons aux cheveux épais-grossiers est revenue à des valeurs comparables à celles des heures du matin; tandis que les valeurs chez les moutons à poils courts sont restées plus élevées (P < 0.05) que celles des heures du matin. Il a été conclu que les moutons Yankasa de type cheveux épais-grossiers avaient une demande thermorégulatrice plus faible pour maintenir l'homéostasie dans les heures de l'après-midi, et refroidi plus rapidement dans les heures du soir par rapport à leur homologue de type cheveux courts lisses pendant la saison chaude-sèche dans la savane tropicale

PSIII-3 Association of heat shock factor protein 1 and prolactin receptor variants with molecular breeding values in Senepol cattle

Thermal stress has been associated with lower food intake and growth rate in beef cattle. The purpose of this study was to assess the segregation of the p.Leu462* nonsense mutation in the prolactin receptor gene (PRLR) responsible for slick hair (SH) phenotype in Senepol and a T &gt;C missense variant (V344A) located in the heat shock transcription factor protein 1 gene (HSF1). We compared the potential association of these polymorphisms with molecular breeding values (MBV) that were estimated using a panel of commercial genetic markers (Igenity, Neogen Corp). For this, 29 females and 21 males were genotyped by PCR and sequencing. Three genotypes were observed for the p.Leu462* with frequencies of 0.02 C/C, 0.16 C/- and 0.82 -/-. For V344A only two genotypes were observed with frequencies of 0.86/TT and 0.14/TC. This polymorphism was in linkage disequilibrium with a C &gt;T synonymous variant; therefore, for the statistical analyses, the HSF1 genotypes were combined as TT/CC and TC/CT. The GLIMMIX procedure and Tukey test of SAS were used (effect of sex, HSF1 and SH genotype and interactions). MBV for production traits such as average daily gain, tenderness, yearling weight (YW), marbling, fat thickness (FT), percent choice (PC), ribeye area (RA) and carcass weight. Effect of sex (P &lt; .05) were found for YW (males: 6.93lbs ± 0.53, female: 5.74lbs ± 0.57) and for PC (female: 16.17±0.75, male: 15.02±0.55). Differences between HSF1 genotype combinations were significant for the MBV of RA (TC/CT: 0.96in2±0.10; TT/CC: 0.781in2±0.07 and for FT (TC/CT: 0.16in±0.02; TTCC: 0.12in±0.01). The similarity in segregation of SH responsible genotypes (C/- and -/-) and HSF1 (TC/CT and TT/CC) in Senepol could indicate a potential role of HSF1 in adaptation to heat stress in cattle with an additional effect in muscling and fat deposition.

13 Changes in Cytokine Profiles in Response to Ergovaline Exposure in Slick vs. Normal Hair Coat in Beef Heifers

Fescue toxicosis is a syndrome common in cattle grazing fescue containing an endophyte that produces ergot alkaloids. Our lab has previously demonstrated that chronic exposure of ergot alkaloids adversely effects innate immune response. Therefore, the objective of this study was to examine changes in cytokine profiles in heat tolerant heifers exposed to ergot alkaloids from endophyte-infected fescue compared to wildtype controls. Angus X Senepol heifers were blocked by weight and hair coat genotype, Slick (S) or Normal (N) then randomly fed novel endophyte fescue (EN) or endophyte-infected fescue (EI) haylage in a total mixed ration for 63d (n=5 per group). Weekly measurements were collected to monitor physiological responses during exposure to ergot alkaloids. Blood samples were collected for cytokine analysis on d 0, 14, 28 and 56. Cytokine concentrations were quantified using Quantibody® Bovine Cytokine Arrays. Data were analyzed using PROC MIXED of SAS with repeated measures. Statistical significance was determined at P&lt; 0.05 and a tendency at 0.05&lt; P&lt; 0.10. Concentrations of TNF were greater in EN-S heifers (6.57 ng/ml) compared to other heifer groups (P&lt; 0.05; 1.33, 2.34, 3.15 ng/ml for EN-N, EI-S, and EI-N, respectively). Concentrations of IL21 were greater in EN-S heifers (8.15 ng/ml) compared to other heifer groups (P&lt; 0.05; 1.55, 3.43, 3.26 ng/ml for EN-N, EI-S, and EI-N, respectively). Concentrations of IFNA (P=0.0543), IFNG (P=0.0558), IL1F1 (P=0.0587), and IL1F5 (P=0.0738) tended to be greater in in EN-S heifers compared to other heifer groups. Interestingly, concentrations of chemokine CCL4 (953.5 vs. 183.7 pg/mL) and CXCL9 (2.57 vs. 0.69 ng/mL) were significantly greater in S heifers than N heifers (P&lt; 0.05). No differences were observed for IL13 and CXCL10 (P &gt;0.05). In contrast to previous data, exposure to ergovaline via endophyte-infected fescue, did not induce an innate immune response. Rather, cytokine concentrations were elevated in heifers with the slick hair genotype. Overall, developing a better understanding of the interaction between ergot alkaloids and the slick hair genotype will help to improve cattle health management.

159 Relationships among circulating prolactin concentrations, hair coat score, and weights of grazing cows

Prolactin (PRL) is a pleiotropic protein hormone synthesized and released from the anterior pituitary. Concentrations of PRL can serve as a biomarker of cattle exposure to ergot alkaloids. Our objective was to determine relationships among prolactin concentrations, hair coat score, and body weights of non-lactating crossbred beef cows (n = 71). Cows were weighed, hair coat scored (1 = 100% shed, and 5 = 0% shed), and blood samples collected in May, June, and July. Cows were grazing mixed grass pastures that included native endophyte-infected tall fescue. Serum PRL concentrations were determined by validated RIA. Based on May samples, cows were categorized as high (n = 11; 159 ± 29 ng/mL PRL), medium (n = 48; 51 ± 4 ng/mL PRL), or low (n = 12; 21 ± 4 ng/ mL PRL). Data were analyzed with Pearson correlations, and repeated measures ANOVA with month and prolactin category (PRLCAT) as main effects. Concentrations of PRL were correlated (r &gt; 0.53; P &lt; 0.0001) over the three months, and May PRL concentrations were correlated (r &gt; 0.29; P &lt; 0.02) with cow body weights in May, June, and July. Cows in the low PRLCAT had lower (P &lt; 0.01) concentrations of PRL in all three months. Hair coat score decreased (P &lt; 0.0001) each month (4.3, 2.7, and 1.3; respectively, May, June, July), and was higher (P &lt; 0.05) for cows with low PRLCAT (3.3 vs. 2.7 and 2.4 for low, medium, and high, respectively). Cow body weight increased (P &lt; 0.0001) from May to July. Cows in the low PRLCAT had lower (P &lt; 0.05) body weights than medium and high PRLCAT cows (484 vs. 555, and 575 kg; respectively). Concentrations of PRL in May could be useful in identifying cattle with slick hair coats and heavier body weights.