María Andrea Cerrillo-Soto

Dietary Chemical Composition, Plasma Metabolites and Hormones in Range Goats

Abstract Juárez-Reyes, A.S., Nevarez-Carrasco, G., Cerrillo-Soto, M.A., Murillo-Ortiz, M., Luginbuhl, J-M., Bernal-Barragán, H. and Ramírez, R.G. 2008. Dietary chemical composition, plasma metabolites and hormones in range goats. J. Appl. Anim. Res, 34: 81–86. The objective of this study was to determine the monthly chemical composition of the diet consumed by range goats and plasma concentrations of glucose, urea, non-esterified fatty acids (NEFA), luteinizing hormone (LH), growth hormone (GH), insulin and progesterone (P4) during lactation (January-June). Three esophageally-cannulated female goats and twelve intact female goats (38±1.7 kg BW) were used to obtain extrusa and blood samples, respectively. Body weight decreased (P<0.05) by 12.5% during the period from January to May, whereas, in June goats lost 250 g d−1. There was a fall in nutrient density during May and June. With the exception of progesterone (0.1–0.6 ng ml−1), LH (7.1–11.0), GH (22.8–30) and insulin (0.6–1.8) increased (P<0.05) as lactation period progressed. It is concluded that plasma metabolite concentrations suggested that an energy supplementation schedule might be necessary during the early lactation period of goats. In addition, if harsh climatic conditions appear at the end of lactation, an increment of 70% in their energy maintenance requirements might be considered to avoid weight losses and to improve body condition of goats prior to breeding season.

Circannual Fluctuations in Serum Cortisol and Glucose Concentrations and Hair Coat Growth in Goats

Abstract Meza-Herrera, C.A., Bocanegra V.J.A., Bañuelos, R, Aréchiga, C.F, Rincón, R.M, Ochoa-Cordero, M.A, Juárez-Reyes, A.S, Cerrillo-Soto, M.A. and Salinas, H. 2007. Circannual fluctuations in serum Cortisol and glucose concentrations and hair coat growth in goats. J. Appl. Anim. Res, 31: 79–82. This study characterized serum Cortisol (CORT) and glucose (GLUC) levels and the hair cover length in six goat genotypes, Granadina (G), Nubian (N), Saanen (S), Toggenburg (T), Alpine (A), Crosses (C; Saanen x Criollo) throughout the four seasons of the year. Goats (five per breed, 37 ±3 mo, 42.1±3 kg) were kept under stall-fed conditions. The heaviest BW was displayed by S and T while the best BC (P<0.001) was observed in C, N and G. The S, T and C displayed the largest (P<0.001) values for rump (HR) and neck (HN) hair cover. However, neither CORT nor GLUC differed (P>0.05) among genotypes. The belly hair cover (HB) and HN were the maximum during winter (Wn) and spring (Sp). During fall (Fl) there was the lowest (P<0.001) BC and the most reduced (P<0.001) GLUC. These findings suggest that goats may perceive to both fall environmental conditions and rainfall as potential stressors able to activate the hypothalamic-hypophyseal-adrenal axis, and in turn, may dictate catabolic actions in a cortisol-dependent fashion.

Nutritional value of Acacia amentacea and Parkinsonia texana grown in semiarid conditions

In order to evaluate the nutritional value of Parkinsonia texana and Acacia amentacea, two leguminosae species of the Tamaulipan scrubland, Northeastern Mexico, two experiments were carried out: the first tested the effects of season and browse species on chemical composition as nutritional variable to small ruminants; the second tested the effect of the addition of polyethylene glycol (PEG) on fermentation parameters. Foliage samples were collected from three sites. Data of chemical composition were analysed using analysis of variance for a bi-factorial arrangement, whereas the effect of PEG was analysed by a strip plot design. Results of chemical composition were affected by interacting factors season*species as individually they were significantly different (P<0.001). Addition of PEG affected (P<0.001) fermentation parameters. Significantly higher values of neutral detergent fibre (42%), condensed tannins (19%), purines (9 μmol), partitioning factor (PF) (6.1) and gross energy losses (GEL=6.7%) were found in A. amentacea, while P. texana gave higher crude protein (18%), in vitro true organic matter digestibility (82%), metabolisable energy (ME) [2.1 Mcal/kg dry matter (DM)], A (183 mL), c (0.07/h) and L (0.86 h). Addition of PEG increased ME, and affected (P<0.001) fermentation parameters A and c, while purines and PF decreased. Results indicate that chemical composition and fermentation parameters vary according to seasons and species. PEG addition increases the fermentation parameters, which indicates that PEG counteracts the detrimental effects of secondary components of samples. Data suggest that using both species combined could supply necessary nutritional requirements to small ruminants in the Tamaulipan scrubland.

Mechanistic Model Evaluation of Tree Species and Cactae Commonly Consumed by Grazing Goats

Abstract Vargas-Villamil, L., Juárez-Reyes, A.S., Ku-Vera, J., Ávila-Vales, E., Vargas-Villamil, F., Medina-Peralta, S. and Cerrillo-Soto, M.A. 2008. Mechanistic model evaluation of tree species and cactae commonly consumed by grazing goats. J. Appl. Anim. Res., 33: 193–198. The mechanistic dynamic model, Kóokay, was used to estimate the initial high degradable phase (QS sc (0)), the medium degradation fractional rate (k ND,NDSm), the fermentation fractional rate (kSm,SmF) and the relation between the produced gas as a function of the fermented mass (f ΔG,ΔF). To obtain these parameters a bounded regression problem was solved using in situ and in vitro data. It was found that: the cactae had much higher value for Qsc(0), k ND,NDSm and k Sm,SmF than tree leaves. The fΔG,ΔF > 40 mLG(mgF)−1 for Q. grisea and Opuntia spp and fΔG,ΔF < 40 mLG(mgF)−1 for the others. At the incubation time of 8 h, the fermentation of the tree leaves, the O. leptocaulis and the Opuntia spp was 20, ∼35 and 60 mgF(100 mgDM)−1, respectively. It was concluded that kSm,SmF is an important parameter to determine the nutritive value of new feeds since it is useful to predict the F into the rumen. Also, the F for Q. grisea, Q. eduardii and A. schaffheri are similar, but lower than Opuntia spp and O. leptocaulis.