Resumen

MIJARES-LOPEZ, H et al. Live-weight change in grazing steers in the tropics: response to multi-nutritional block supplementation. Universidad y ciencia [online]. 2012, vol.28, n.1, pp.39-49. ISSN 0186-2979.

The objective of this study was to evaluate the response, through live-weight change, of steers grazing on African star grass (Cynodon plectostachyus), to supplementation with multi-nutritional block during 90 days, under tropical conditions in Mexico. Thirty steers, with an average initial weight of 360 ± 30 kg, were used. They were placed in three groups of 10 animals and randomly assigned the treatments: 1) grazing+multi-nutritional block, 2) grazing+traditional supplement and 3) only grazing, in a completely random design. The rotational grazing system had three days of occupation and 27 days of rest. The average forage that was provided had 5,312 kg dry matter (MS) ha-¹ with 6.8% of crude protein, FDN 74.0%, FDA 51.9%, and in situ digestibility 38.5%. The total intake of dry matter was greater (p < 0.01) in treatment three (14.4 kg MS animal-¹ d-¹) compared with treatments one and two (10.7 kg and 13.4 kg MS animal-¹ d -1 respectively). Against what was expected, the daily live-weight gain was similar (p > 0.05) among treatments, averaging 0.43 kg animal-¹ d-¹. This response was mainly due to the fact that the multi-nutritional block did not increase the decomposition rate of the forage or the production of volatile fatty acids in the rumen. Under the conditions of this study, supplementing grazing steers with multi-nutritional block did not represent any benefit.

Palabras llave : Grazing; intake; live-weight change.

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