Associação ureia-palma orelha de elefante mexicana (Opuntia stricta (Haw.) Haw na alimentação de ovinos de corte

Abstract

The objective of this study was to evaluate effects of diets based on Orelha de Elefante Mexicana (OEM) (Opuntia stricta (Haw.) Haw with increasing levels of urea in replacing soybean meal on nutrient intake and digestibility, nitrogen balance (NB), blood metabolites, performance, carcass characteristics and composition, physicochemical composition, quality and sensorial attributes of feedlot Santa Inês sheep. Forty non-castrated Santa Inês lambs, with an average initial body weight of 22.2 ± 2.1 kg, were distributed in a completely randomized design, with four treatments and 10 replications. The treatments consisted of four diets based on palm oil associated with increasing levels of urea (0; 7.3; 14.6 and 21.9 g/kg DM) replacing soybean meal. The addition of urea in diets based on OEM cactus were not influence (P > 0,05) intake of dry matter (DM), organic matter (OM), neutral detergent fiber (acpNDF), total digestive nutrients (TDN) (g/day) and DM (%BW-0.75), but increased (P = 0,035) the intake of DM (%BW), the intake (g/day) of crude protein (CP) (P = 0,018), ether extract (EE) (P = 0,000) and non-fiber carbohydrates (NFC) (P = 0,028), without influencing (P > 0,05) the apparent digestibility coefficients of DM, OM, CP, EE, acpNDF and NFC. The amounts of ingested nitrogen (N), fecal N, absorbed N (g/day) or retained N and absorbed N (% ingested) were not influenced, but urinary N (g/day), and retained N (% ingested) were influenced (P = 0,009 and P = 0,000) with maximum values (9,5 and 44,5 g/day) in levels (7,3 and 21,9 g/kg DM) of urea respectively. However, triglycerides and albumin concentrations were influenced (P = 0,003 and P = 0,015) with maximum values (22,4 and 2,9 g/dL) observed at levels (14,6 and 0,0 g/kg DM) of urea, respectively. The concentrations of lactate (P < 0,000), gamma-glutamyltransferase (P < 0,000), alkaline phosphatase (P = 0,013) and calcium (P < 0,020) and potassium (P < 0,002) concentrations increased. The body weight at slaughter, total weight gain and average daily gain decreased linearly (P = 0,029, P = 0,003, P = 0,003) respectively, while feed conversion increased (P = 0,000). Empty body weight (P = 0.009), hot carcass weight (P = 0.023) and cold carcass weight (P = 0.015) decreased with the addition of urea. However, the contents of the gastrointestinal tract, hot carcass yield, cold carcass yield, carcass compactness index, carcass conformation and finishing fat were not influenced (P > 0.05). The perirenal fat was influenced (P < 0.003), with maximum fat indices (2.20) on levels (0 and 21.9 g/kg DM) of urea end the weight of the liver, lungs + trachea and kidneys decreased (P = 0,030, P = 0,002, P = 0,001), respectively. The commercial meat cuts, leg weight (P = 0.037) and loin yield (P = 0.027) decreased linearly, while shoulder yield was influenced (P = 0.024) with higher yield (20.20%) at the level (14.6 g/kg DM) of urea. Regarding the tissue composition of the leg, the weight of the Semitendinosus muscle (P = 0.036), Adductor muscle (P = 0.023), weight of the 5 leg muscles (P = 0.018) and leg muscularity index (P = 0.019) decreased linearly. In addition, bone weight, bone yield, muscle/bone ratio were influenced (P = 0.047, P = 0.006, P = 0.014) with maximum values (552 g, 20.69%, 3.5) in the levels (14.6; 7.3; 21.9) of urea respectively. The parameters evaluated in the meat, pH, water holding capacity, color parameters (L*, a*, b*), moisture content, crude protein and ash were not influenced (P > 0.05). However, cooking loss (P = 0.002) and shear force (P = 0.044) decreased linearly, while the lipids content increased linearly (P = 0.047). There was no difference (P > 0.05) for meat sensory attributes such as general appearance, color, aroma, tenderness, juiciness and flavor. Orelha de Elefante Mexicana spineless cactus based diets, can partially or completely replace soybean meal in the diet of feedlot lambs without without changing dry matter intake, total digestible nutrient intake, apparent dry matter and nutrient digestibility, obtaining a positive N balance, not compromising the characteristics and carcass yield, in addition to improving the qualitative characteristics of the meat without interfering with sensory attributes. However, it reduces performance and increases feed conversion.