Relationship between body weight and scrotal circumference in growing Pelibuey sheep raised under tropical conditions / Relação entre o peso corporal e a circunferência escrotal em ovinos Pelibuey em crescimento criados em condições tropicais

The body weight (BW) of an animal is a vital economic trait that might help in decision-making in the handling of animals. The objective of the present study was to develop equations for the prediction of BW in Pelibuey sheep using scrotal circumference (SC). The BW (23.40 ± 6.96 kg) and SC (20.25 ± 6.19 cm) have been recorded in 405 male Pelibuey at the Southeastern Center for Ovine Integration, Mexico. Linear, logarithmic, quadratic, exponential, cubic, and power regression models were used for data analysis. Pearson correlation (R), Coefficient of determination (R2), Adjusted coefficient of determination (Adj.R2) Root mean square error (RMSE), Akaike information criterion (AIC), and Bayesian information criterion (BIC) were used to select the best model. Power regression model showed the highest R (0.93), R2 (0.86), Adj.R2 (0.86) and lowest RMSE (0.02), AIC (-989.44) and BIC (-981.44). The current study suggests that SC might be used as the only predictor for BW of growing Pelibuey sheep raised under tropical conditions.

O peso corporal (PC) do animal é uma característica econômica importante, que pode auxiliar na tomada de decisões no manejo dos animais. O objetivo do presente estudo foi desenvolver equações para a predição do PC em ovinos Pelibuey por meio da circunferência escrotal (CE). O PC (23,40±6,96kg) e a CE (20,25±6,19cm) foram registrados em 405 ovinos machos da raça Pelibuey no Centro de Integração Ovina da Região Sudeste do México. Os modelos lineares, logarítmicos, quadráticos, exponenciais, cúbicos e de regressão de potência foram utilizados para a análise dos dados. A correlação de Pearson (R), o coeficiente de determinação (R2), o coeficiente de determinação ajustado (Adj.R2), o erro do quadrado médio (EQM), o critério de informação de Akaike (AIC) e o critério de informação bayesiano (BIC) foram usados para selecionar o melhor modelo. O modelo de regressão de potência apresentou maiores R (0,93), R2 (0,86), Adj.R2 (0,86) e menores EQM (0,02), AIC (-989,44) e BIC (-981,44). O estudo atual sugere que a CE pode ser usada como um único preditor para o PC de ovinos Pelibuey em crescimento criadas em condições tropicais.

Haemonchus contortus infection induces a variable immune response in resistant and susceptible Pelibuey sheep.

The immune response and phenotypic characteristics of Pelibuey lambs were analysed after the induction of a Haemonchus contortus trickle infection. Male lambs (n = 29; 20 kg live weight) were infected with 100 H. contortus infective larvae per kg of live weight on day 3, 5 and 7 of the experiment. The number of eggs per gram (epg), seven haematological parameters and the immunoglobulin A (IgA) level were analysed for 56 experimental days. In addition, histopathological samples from the fundic abomasal region and the relative expression of 10 immune-related genes from 15 infected and three non-infected lambs were analysed at day 0 and 49 of the experiment. The epg count and some haematological parameters (leucocytes, red blood cells, haemoglobin and total protein) with statistically significant differences (P < 0.01) were used to identify nine resistant and 20 susceptible lambs (1166 ±â€¯1071 and 3171 ±â€¯1463 epg, respectively). Moreover, acute infiltration of immune cells and parasitic granuloma formation were observed in susceptible lambs; the resistant group had moderate inflammatory cell infiltration. With respect to relative gene expression, resistant lambs showed upregulation (P < 0.001) of 10 genes, from 2.2 to 15.99 fold. Moreover, there was a strong indirect correlation (P < 0.05) between the epg count and interleukin 5 (IL5) gene expression. By contrast, there was an average 0.34 fold downregulation in nine of the immune-related genes (P ≤ 0.05) in susceptible lambs (the only exception was Fc fragment of IgE receptor Ia [FCER1A] upregulation). In addition, there was a direct correlation (P ≤ 0.05) between the epg count and the expression of IL8, which encodes an inflammatory chemokine. In conclusion, this study showed differential IL5 and IL8 gene expression during haemonchosis in resistant and susceptible Pelibuey lambs, respectively, together with a variable immune response based on histopathological and haematological parameters.

Effect of different combinations of soybean-maize silage on its chemical composition, nutrient intake, degradability, and performance of Pelibuey lambs.

Sheep raising in the state of Guerrero, México, is a primary activity that is worth about US$3,251,931 annually. The objective of the present study was to evaluate the chemical composition, degradability, nutrient intake, and animal performance of Pelibuey lambs fed on different combinations of maize-soybean silages. Twenty-one combinations of maize silage (MS) and soybean silage (SS) were evaluated at day 45 post-ensiling; in each combination, MS was replaced by 5 % of SS. The 21 combinations were analysed for crude protein (CP) and chemical composition. In order to obtain a statistical criterion of potential treatments for the animal feeding test, a cluster analysis was performed based on the CP contents of all combinations at day 45 post-ensiling. From cluster analysis, four treatments were selected T1 = 100-0 % (MS/SS), T8 = 65-35 %, T12 = 45-55 %, and T16 = 25-75 %. Results indicated that cluster analysis was useful for identifying the potential treatments for animal feeding based on the crude protein content. The dry matter (DM), organic matter (OM), and acid detergent lignin (ADL) contents did not declined significantly (P > 0.05) during the fermentation of silages but CP content decreased from day 0 to 45 post-ensiling. The treatment with the highest estimated microbial crude protein synthesis was T8 and it showed the highest metabolizable energy intake, high feed efficiency with a forage-concentrate ratio of 84:16.

Composición corporal de corderos Pelibuey en función de la concentración energética de la dieta y del peso al sacrificio / Body composition in Pelibuey lambs in terms of feed energy concentration and slaughter weight

With the aim to study the effects of dietary energy and the slaughter weight on the carcass yield and characteristics of Pelibuey male lambs, the regional structure and tissue composition of 32 half carcasses, as well as the deposition pattern of visceral fat and its unsaturated fatty acid degree was assessed. The animals were fed two diets containing the same amount of crude protein (14.1%), but different energy density, diet I (D-I): 2.60 and diet II (D-II): 2.85 Mcal ME/kg DM. Lambs were slaughtered at 30, 37, 44 and 51 kg body weight. The data were analyzed on a completely randomized design with a factorial 2 × 4 arrangement. The commercial yield (%) differed (P < 0.05) between diets (DI: 46.2 and D-II: 49.3) and between slaughter weights, increasing as the body weight increased. Neither diet nor the slaughter weight affected the carcass cuts; the piece that represented the highest percentage was the thorax (32.3%), followed by the leg (31.2%), shoulder (17.6%), abdomen (12.3%) and neck (6.7%). The D-II resulted in greater proportion of muscle (65.9%) than the DI (64.7%): as the slaughter weight increased so the fat did at the expense of bone and muscle. The energy density of the diet led to differences (P < 0.05) in the amount of visceral fat (D-I: 5.8 ± 0.7 and D-II 7.0 ± 0.8), in the degree of unsaturated fatty acids (D-I: 39.2 ± 2.6 and D-II: 44.9 ± 2.8) and its deposition pattern (D-I: 51.7 ± 0.9; 48.3 ± 0.6 and D-II: 46.7 ± 0.6; 53.3 ± 0.8, respective percentages to carcass and viscera).

Con el propósito de estudiar los efectos del nivel energético de la dieta y del peso al sacrificio sobre las características de la canal de corderos Pelibuey, se evaluó la estructura regional y la composición tisular de 32 medias canales, así como el patrón de acumulación de la grasa visceral y su grado de insaturación. Los animales fueron alimentados con dos dietas isoproteínicas (14.1% PC) de diferente densidad energética, dieta I (D-I): 2.60 y dieta II (D-II): 2.85 Mcal de EM/kg MS. Los corderos se sacrificaron a los 30, 37, 44 y 51 kg de peso corporal. Los datos obtenidos se analizaron en un diseño completamente al azar con arreglo factorial 2 × 4. El rendimiento comercial en canal (%) difirió (P < 0.05) entre dietas (D-I: 46.2 y D-II: 49.3) y entre pesos al sacrificio, incrementándose conforme se elevó el peso vivo. Ni la dieta ni el peso al sacrificio afectaron los cortes de la canal; la pieza que representó el mayor porcentaje fue el tórax (32.3%), seguido de la pierna (31.2%), espaldilla (17.6%), abdomen (12.3%) y cuello (6.7%). La D-II originó mayor proporción de músculo (65.9%) que la D-I (64.7%), al incrementarse el peso al sacrificio se elevó la cantidad de grasa a costa de una reducción del hueso y músculo. La densidad energética de la dieta propició diferencias (P < 0.05) en la cantidad de grasa visceral (D-I: 5.8 ± 0.7 y D-II: 7.0 ± 0.8), en el grado de insaturación (D-I: 39.2 ± 2.6 y D-II: 44.9 ± 2.8) y en su patrón de depósito (D-I: 51.7 ± 0.9; 48.3 ± 0.6 y D-II: 46.7 ± 0.6; 53.3 ± 0.8, porcentajes respectivos para la canal y las vísceras).