Resumo

BORQUEZ-GASTELUM, José Luis et al. Yield performance of growing lambs fed silages with poultry litter, pig excreta and urea with molasses cane or a bakery by-product. Agrociencia [online]. 2018, vol.52, n.3, pp.333-346. ISSN 2521-9766.

Livestock excreta are made up of fractions of undigested feed and other nutrients that are incorporated in the animal’s digestive tube. Their production and accumulation are a source of environmental pollution, but they are also a valuable source of nitrogen and minerals for feeding ruminants. The objective of this study was to evaluate diets with corn stover silage, sugarcane molasses (MOL) and bakery by-products (BPP) as sources of hydro-soluble carbohydrates (C), mixed with fresh pig excreta (FPE), dehydrated poultry litter (DPL), and agricultural urea (UR) as sources of nitrogen (N) and their effect on lamb growth and carcass characteristics. The lambs received diets with 145 g PC kg-1 DM and 10 MJ EM kg-1 DM, plus 400 g kg-1 (DM) silage for 60 d. After this time, the lambs were sacrificed to measure productive variables and carcass quality. Dry matter intake (DMI) was analyzed with repeated measures. For yield, fat deposit, and morphometry, a random blocks design was used with a 2 x 3 factorial array. Qualitative variables were analyzed with the Kruskal-Wallis test. Least squares means of DMI at 60 d were not different (p > 0.05) among treatments. However, there was an effect (p≤0.05) of N source on daily weight gain (DWG) and NxC interaction for leg width and thoracic fat thickness. Source of C affected (p≤0.05) yield of leg perimeter, loin area and depth of sub-cutaneous fat. Carcass conformation was inferior (p≤0.05) for the combination BBP with UR; with the other treatments, conformation scores of R to U were obtained. The BBP treatment with FPE caused more (p≤0.05) external fat covering, light pink meat and cream-colored fat. The conclusion is that lambs fed silaged FPE and BBP had carcasses with better conformation and fat.

Palavras-chave : carcass characteristics; excreta; silage; cane molasses; bakery by-products.

        · resumo em Espanhol     · texto em Espanhol | Inglês     · Inglês ( pdf ) | Espanhol ( pdf )