The aim of this study was to describe the morphology and estimate live weight from body measurements of Socorro Island Merino lambs. A group of Socorro Island Merino lambs was recorded from birth to year for live weight, rump width, rump length, withers height, body length, cannon bone perimeter, and chest girth, width, and depth. The effect of the lamb type on body measurements and live weight was analyzed using ANOVA, Pearson’s correlation analysis was performed to estimate the relationship between body measurements and live weight, multiple linear regressions were fitted to obtain prediction equations of live weight from the body measurements and finally, chest girth was used to generate prediction equations using linear and exponential models. At birth and at year, differences were observed in body measurements, especially those related to the thoracic region, with crossbred males showing the highest values. Live weight was correlated with almost all the body measurements, with the highest coefficients observed with chest girth, chest width, and chest depth. Live weight can be accurately predicted from multiple regression equations using several body measurements, but using only chest girth (CG) as a predictor, the exponential equation W_0–365 = 0.9142 exp^{(0.0462 CG)} showed the best accuracy.

The aims of this study were to evaluate the effect of genetic and non-genetic factors on the growth of Socorro Island Merino lambs and to model their growth curve using nonlinear mathematical models. The weight of 41 Socorro Island Merino lambs was recorded at birth and at 45, 90, 135, 180, 225, 270, 315 and 365 days of life from May 2019 to September 2021. The effects on growth of sex, genotype, year of birth, and parity of the dam were analyzed. Four non-linear models (Brody, Logistic, Gompertz and von Bertalanffy) were fitted for determining the best model to describe growth curve. Birth weight and pre-weaning growth rate were not affected (P 0.05) by any of the factors studied, while weaning weight was only significantly affected (P 0.05) by sex. Year of birth significantly affected (P 0.05) post-weaning growth rate and weight of the lamb from 270 days, while sex significantly affected (P 0.05) weight at 315 days. The Gompertz and Brody models were the best fitted to describe growth curves of lambs. Purebred males showed a larger response to increasing levels of energy-protein supplementation, while they had greater mature weight and lower maturation rate compared to females and crossbred males. In conclusion, knowledge of growth and factors influencing growth pattern can help implement appropriate management strategies and make decisions aimed at the conservation of Socorro Island Merino lambs.

Background. Propylene glycol has been used successfully since the 1950’s for him acute and prophylactic treatment of ketosis in dairy cows however; its use has been poorly evaluated in beef cattle and meat sheep. Objective. Evaluate the effects of different doses of propylene glycol on the productive parameters, blood metabolites and ruminal parameters in fattening lambs. Methodology. Twenty lambs 14.70 ±0.57 kg of weigh, 2 months old, males and Katahdin-Black Belly breed, were randomly assigned to one of four treatments, a control mixed ration and an experimental diet with three different levels of propylene glycol: 1.0, 1.5 and 2.0 g/20 kg live weight/day. The effects of propylene glycol on blood metabolites, ruminal and productive parameters were assessed. Results. Propylene glycol supplementation did not affect (P>0.05) glucose, total lipids, triglycerides and cholesterol concentration as well as increased (P<0.05) the concentration of beta hydroxybutyrate. In addition, its inclusion resulted in an increase in pH and protozoa population and in a decrease of reductive activity (P0.05) on feed intake, weight gain and feed conversion ratio of lambs but carcass yield was improved without increasing the feeding cost of production. Implications. Propylene glycol is a viable option as an energy source in fattening lambs. Conclusion. Inclusion of PPG increased the pH and the population of ruminal protozoa, reduced the formation of ketone bodies and improved the carcass yield of lambs without increasing the meat production cost.

En este estudio se realizó el análisis de bagazo de cervecería de la Planta cervecera de Modelo en Calera, Zacatecas el cuál se utiliza como ingrediente alternativo en las dietas de ganado lechero Se utilizó la muestra integra de bagazo de cervecería, la cual fue sometida a una deshidratación y posteriormente fue molido. Se realizó un análisis químico-proximal mediante el método de Van Soest, los resultados de la proteína y extracto etéreo del bagazo de cervecería fueron superiores a los comparados por la literatura citada (29.14% y 9.64%)), demostrando que es un ingrediente sumamente viable. Se realizó digestibilidad in situ e in vitro, para identificar el comportamiento del ingrediente dentro de los animales . La digestibilidad del bagazo de cervecería (25% a las 24 horas) fue menor a los controles utilizados, sin embargo fue efectiva (99.9% a las 144 horas). De esta manera se comprueba que el bagazo de cervecería es un ingrediente con altos valores nutricionales que permite mejorar la producción e incrementar la rentabilidad de los establos de los pequeños productores en el país.