Substituição da silagem de sorgo por resíduo da cultura de milho na alimentação de cordeiros confinados

Abstract

The objective of this study was to evaluate the effect of sorghum silage substitution by corn crop residue on digestibility, performance, carcass characteristics, leg tissue composition, meat quality and non-carcass component of lambs Santa Inês x Dorper finished in confinement. The research was conducted at the Benjamim Maranhão Experimental Station, belonging to the State Agricultural Research Company of Paraíba (EMEPA-PB), located in the municipality Tacima - PB. Four treatments (0, 33, 66 and 100%) were evaluated, which consisted of residue levels of the corn crop, replacing sorghum silage, in a completely randomized design. Thirty-six male lambs were used, with an average body weight of 24.44 ± 2.93 kg and 150 days of age. The animals were housed in individual stalls and the feed offered twice a day. The nutrient intake was quantified by difference between the fractions present in the supply and in the leftovers. A digestibility test was carried out, during which the food and feces leftovers were collected at different times (7:00 a.m., 9:00 a.m., 11:00 a.m., 1:00 p.m. and 3h00 p.m.) for five days, directly in the rectal ampulla. The weight gain was obtained by the difference between the final weight and the initial weight of the animals. The weight performance of the animals was verified by weighing every 14 days. After 21 days of adaptation and 68 days of experimental, the animals were slaughtered, and the weights of the body constituents registered. The organs, viscera and by-products of the slaughter were quantified and had their weights recorded. The carcasses were weighed, then the pH was measured, and the temperature was taken at 0h and then stored in a cold room at 4ºC for 24h. Morphometric measurements were performed on the cold carcass. Subsequently, they were sectioned in five commercial cuts. The leg was dissected and the tissues quantified in a sample of Semimembranosus were performed the centesimal analyzes of the meat. In the left loin, measurements of color, water retention capacity, cooking losses and shear force were performed. The substitution of sorghum silage by maize crop residue linearly decreased organic matter intake. The coefficients of apparent digestibility of dry matter, organic matter and total carbohydrates increased linearly. The rates of gain in weight were influenced by the substitution of silage; however, the feed conversion and feed efficiency were not influenced. The replacement of silage in lambs fed linearly increased liver, heart, spleen and esophagus weights, for the other organs and viscera, no effects of treatments were observed. There was a linear decreasing effect for hot and cold carcass weights (kg), and hot and commercial carcass yields. For the morphometric measurements of the carcass, except for the perimeter of croup, there was no influence of the substitution of sorghum silage for any of the measurements. Increasing levels of corn crop residues in lamb feed decreased leg, shoulder and rib weights. The weight of the reconstituted leg was influenced by the treatments; however, the leg components and muscle index had no effect. There was no effect of the substitution of the silage on the tissue composition of the leg (%), muscle: bone ratio, muscle ratio or leg muscle index, but had an effect on (%) bone and other tissues. The physical-chemical parameters of the meat (color, shear force, water retention capacity and cooking losses) were not influenced by the substitution of silage for corn residue in the lamb‘s diet. There was no effect on the moisture content, crude protein, mineral matter and ethereal extract of lamb meat. The substitution of sorghum silage by maize crop residues in the feed of finished lambs in feedlot adversely affects dry matter intake, organic matter and consequently weight performance, hot and commercial carcass yields. However, it does not affect the characteristics and morphometry of carcass, tissue composition of the leg, and the physical-chemical and centesimal characteristics of F1 Santa Inês x Dorper lamb meat.