Beef cows were used to determine the influence of calcium soaps of fatty acids (CSFA) incorporated in a range supplement on postpartum reproductive characteristics and growth of calves. Cows were assigned randomly to receive 0 (C, n = 68) or 125 g/d of CSFA (M, n = 66). Diets were isonitrogenous (23%) and were used during 105 d, beginning at 61 +/- 36 d (range) precalving. Two blood samples were collected monthly (7-d intervals). Weights of calves at 35, 50, and 90 d of age and weaning weight adjusted to 200 d of age were greater in M than in C (46.8 vs 43.8 kg, P < .05; 56.0 vs 50.6 kg, P< .01; 98.8 vs 91.8 kg, P < .01; and 186 vs 173 kg, P < .01, respectively). Body weights at 35 and 50 d postcalving were greater in M than in C cows (334 and 310 kg, P < .01; 329 and 300 kg, P < .01, respectively). A similar tendency was observed in body condition scores in the same postpartum periods (4.1 vs 3.4, P < .01 and 3.6 vs 2.5, P < .01 for M and C, respectively). Concentrations of total cholesterol, high-density lipoprotein cholesterol, low-density lipoprotein cholesterol, very-low-density lipoprotein cholesterol, and triglycerides were greater (P < .01) in M than in C cows. Percentage of cycling (progesterone > 1 ng/mL) cows at 30 to 90 d postpartum was 38% in M and 22% in C (P < .02). Percentage of pregnant cows during the first half of the breeding season was greater (P < .02) in M (62.5%) than in C cows (35.5%). We concluded that CSFA incorporated in a range supplement during pre- and postpartum periods improved reproductive efficiency and growth of calves.

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Objetivo. Comparar algunas respuestas fisiológicas al calor y humedad atmosférica entre bovinos Chinampos (Bos taurus; Ch), ½ Charolais ½ Brahman (CB), Holstein (H) y Jersey (J). Materiales y métodos. Se realizó un estudio en La Paz, México. Se utilizaron 12 vacas H, 10 J, 15 Ch y 8 CB. Durante el verano se midieron cada semana (a las 0600 y 1600 horas) la frecuencia respiratoria (FR) y temperatura rectal (TR). Se registraron las variables climáticas para calcular el índice de temperatura-humedad (ITH). Resultados. Durante todo el verano, la FR en los cuatro grupos estuvo por encima de los valores fisiológicos para el ganado bovino, siendo superior en H y J que en Ch y CB (p

Efecto de la suplementación de grasas sobre las concentraciones séricas de progesterona, insulina, somatotropina y algunos metabolitos de los lípidos en ovejas PelibueyEffect of fat supplementation on serum concentrations of progesterone, insulin, growth hormone and some lipid metabolites in Pelibuey ewes SummARyIn this study, multiparous Pelibuey ewes were used to determine the influence of calcium soap of fatty acids (CSFA) and bovine fat in the diet on serum concentrations of insulin, somatotropin, progesterone and lipid metabolites (total cholesterol, high and low density lipoproteins and triglycerides). Ewes (n = 6 per group) were assigned randomly to a diet that contained 1.5% CSFA (CS) or 1.2% bovine fat (S), or to a control diet (T) with no additional fat. The diets were provided during 75 days. Weight gain among treatments was similar (P > 0.05). The concentrations of lipid metabolites and progesterone were not affected by the diet (P > 0.05). Insulin concentration was higher (P < 0.01) in ewes that consumed additional fat and higher (P < 0.001) in S than in T and CS. The somatotropin concentration was lower (P < 0.05) in ewes of groups CS and S than in T. The number and size of pulses of somatotropin among treatments were similar (P > 0.05). In conclusion, bovine fat and calcium soap of fatty acids incorporated in the diet of Pelibuey ewes, in the indicated proportions, did not affect weight gain, progesterone concentration or lipid metabolites, but the bovine fat increased the serum concentration of insulin, reducing that of somatotropin.Palabras clave: ovejas Pelibuey, suplementación de grasa, hormonas, metabolitos de lípidos.