Abstract
The study verified the influence of different nutritional levels of the dams, before parturition, the weaning age of the lambs and the finishing system on lamb muscle fiber morphology and meat quality. Ile-de-France × Bergamacia crossbred dams grazing on natural grassland were divided into two groups: 1) nutritional supplement 30 days before the parturition (SUPL), and 2) no nutritional supplement (NS). These groups were further subdivided by weaning age of the lambs, which corresponded to either 45 or 60 days. The weaned lambs from each of the previous groups were also divided into different finishing systems: confined and fed a complete diet (CD), confined and fed hay (H) and kept on grassland (P). The lambs were slaughtered at 30 kg live weight (CD and P), or at 150 days of age (H). The carcasses were cooled at 4ºC/24h. The analyzed variables were: longissimus dorsi muscle fiber morphophysiology, post mortem myofibrillar fragmentation (at 0, 3 and 7 days post mortem), meat pH and temperature. There was no effect of supplementation of dams or weaning age of the lambs for the evaluated variables. The frequency of slow-oxidative (SO), fast-oxidative-glycolytic (FOG) and fast-glycolytic (FG) muscle fiber types was not altered by the treatments, but the fiber cross-sectional area was smaller for the lambs finished only on hay, and the meat pH values and temperature were lower and the myofibrill fragment dimensions were smaller. As time maturation increased from 0 to 3 and 7 days post mortem, there was a decrease in the length of the myofibrill fragments. The diet of the lambs which were maintained confined and fed only with hay was nutritionally inferior when compared with all the others, and this changed the quality of the meat compared to the finishing systems on grassland or confined and fed complete diet.
Highlights
Ruminants, due to their characteristic digestive system, obtain nutrients from fibrous feeds, such as roughage (Van Soest, 1994), which is an advantage to the producer, since the finishing phase on pastures is less labor intensive compared to feedlots and presents lower fixed costs in building maintenance
The objective of this study was to evaluate the consequences of prepartum food supplementation of ewes, weaning age of the offsprings and the finishing system of the lambs on the myofiber type and size and meat quality attributes
The lambs finished on pasture plus supplementation and those in feedlot on complete diet had similar slaughter age and live weight
Summary
Due to their characteristic digestive system, obtain nutrients from fibrous feeds, such as roughage (Van Soest, 1994), which is an advantage to the producer, since the finishing phase on pastures is less labor intensive compared to feedlots and presents lower fixed costs in building maintenance. A major problem in animals kept on pastures is nutritional deficiency, where they certainly experience great variability in protein, energy and fiber content in the forage during a year (dry and rainy season). In the feedlot, this problem is solved because there is consistency in feed quality and quantity offered and parasite infestation much lower than in pastures. Moderate malnutrition of ewes during early pregnancy did not affect muscle development of the offsprings and the myofiber number, and there is a growing interest in studying feed restriction during pregnancy (Greenwood et al, 2000). Lambs under restricted feeding presented myofiber atrophy and slower post mortem pH drop in the muscle (Lefaucherur & Gerrard, 1998), which altered meat quality
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