Relação volumoso: concentrado associado ao tamanho de partícula de feno na terminação de cordeiros

Abstract

The objective of this study was to evaluate the selectivity, intake, ingestive behavior, performance and meat quality of lambs fed different ratios: concentrate (v: c), associated with different particle sizes of hay. Seventy - two male lambs, of the Santa Inês breed, with a mean initial weight of 23.5 kg and age between 3 and 4 months, were confined for a period of 85 days. The animals were distributed in a completely randomized design, and treatments were arranged in a 2 x 2 factorial scheme (Tifton-85 hay processing sieve diameter (13 and 6 mm) and v: c ratio (70:30 and 50: 50). There was interaction (P <0.05) between the diameter of the hay sieve and the v: c ratios in the particle sizes consumed, since the reduction in particle size of the diet decreases the selectivity of the animals. Dry matter and nutrient intakes and ingestive behavior were influenced (P <0.05) by the reduction of the hay sieve diameter and the increase in the proportion of concentrate in the diet, separately. The nitrogen (N) metabolism was influenced (p <0.05) by the change in the v: c ratio, being that diets with a higher proportion of voluminous decreased the consumption of N. There was interaction (P <0.05) between the factors tested in the animal performance, being the best results of sheep fed with 50:50 ratio, regardless of hay processing. The interaction caused effect (P <0.05) for pH 24h after refrigeration and color parameters red intensity and saturation index. Hay processing influenced (P <0.05) the protein content of the Longissimus lumborum muscle, being the highest protein content observed in the meat of lambs fed on coarsely processed hay. The relation v: c influenced (p <0.05) the carcass characteristics, being the greater results for the diets that contained 50% of concentrate, and the luminosity index of the meat color (p = 0.036) being that the result was higher in lamb meat receiving diets containing 70% of roughage. The fatty acid profile (AG) was influenced by the v: c ratio, with saturated fatty acids, C17: 1, conjugated linoleic acid, C18: 3, C20: 5, C22: 5, C22: 6, (AGS), n-3 and thrombogenicity index were higher in Longissumus lumborum of lambs fed v: c ratio 70: 30, in contrast, AG C14: 1, C16: 1-cis 9, C18: 1-cis 9, ΣAGM, n-6: n-3, h: H ratio, Δ9desaturase-C16 and C18 enzyme activity were highest with v: c ratio of 50:50. The processing of hay more finely in diets with high voluminous proportions increases the consumption of the animals due to the smaller selectivity, and the meat of these animals has larger deposits of n-3 PUFA.