Cristiano Sales Prado

Genótipo e condição sexual no desempenho e nas características de carcaça de bovinos de corte superjovens

Ninety-six young beef males were allotted to a completely randomized design in a 4x3 factorial scheme, four genetic groups, Nellore (N), ½ Simmental ½ Nellore (SN), ½ Red Angus ½ Nellore (AN) and ½ Red Angus ¼ Simmental ¼ Nellore (ASN), and three sex conditions (SC), intact (I), castrated (C) and castrated plus Synovex S ® implant (CS). Males were castrated at six months of age, and feedlot started two months later, with the animals being fed with a 70% chopped sugar cane : 30% concentrate diet. Steers were weighted with 28 days intervals, after 16 hours fastening, and were slaughtered with 13 to 15 month of age. The statistical analyses were performed with the MINITAB program. The effects of genotype (G), SC and G x SC on performance and carcass characteristics, were evaluated. Slaughter (SW) and hot carcass weight (HCW) were affected by G. The SN presented the highest SW (389.3 kg) and AN the lowest (343.1 kg). SC affected SW, HCW and finishing degree (FD). I and CS males were heavier at slaughter (373.8 and 375.2 kg, respectively) than C (341,2 kg). The lowest HCW was observed for C steers (180,6 kg), differing (P<.02) from I (197 kg) and CS (201,3 kg). CS steers showed better FD (2,17 points) than the other SC. The SC showed tendency (P< .07) to influence ribeye area, with CS steers showing larger area (65.2 cm2). The G x SC interaction was significant for average daily gain and carcass dressing percentage. When adjusted for initial weight, the interaction was significant for SW, and when adjusted for SW the interaction was significant for HCW. The Simmental crosses were heavier at slaughter. Castration at six months reduced the feedlot performance of young males. The Synovex S® implant increased the finishing degree of the castrated steers carcasses.

Effects of chilling rate and spray-chilling on weight loss and tenderness in beef strip loin steaks

We evaluated the effects of chilling rate and the use of a spray-chilling system on the weight loss by evaporation on carcasses. We also evaluated the effects on meat purge in vacuum package, cooking losses, and on parameters related to the tenderness of strip loin steaks (M. longissimus lumborum). Forty non-castrated males of approximately 12 months old, finished in feed-lot were harvested in 16 Montana cattle (a composite breed), and 24 SimmentalxNellore crossbred cattle. After bleeding, the bodies were electrically stimulated and assigned to one of the four treatments: conventional air-chilling (CAC), conventional spray-chilling (CSC), slow air-chilling (SAC), and slow spray-chilling (SSC). Strip loin steaks (M. longissimus lumborum) of approximately 2.5 cm thick were removed, vacuum packed and aged for 7, 14, 30 or 60 days. Samples were analyzed for sarcomere length, myofibrillar fragmentation index, Warner-Bratzler shear force, and weight losses by purge and cooking. Spraying was efficient in reducing weight loss by evaporation (P<0.05). Effects of treatments and aging period on purge losses were observed, where samples from sprayed carcasses or aged cuts showed higher losses. Cooking losses were not affected either by spraying or aging. The slow chilling, with or without spraying, was more efficient in producing strip loin steaks with lower average shear force and longer sarcomere. The myofibrillar fragmentation index increased with aging time, but was not affected by carcasses spraying.

Farelo de mesocarpo de babaçu (Orbygnia sp.) na terminação de bovinos: composição física da carcaça e qualidade da carne

We evaluated the carcass composition and meat qualitative characteristics, of 30 young crossbred bulls (18.9 months and 346.8kg) fed with diets with different proportion of babassu mesocarp bran (BMB) (Orbygnia sp.); replacing corn: 0, 25, 50, 70 and 100% substitution. The percentage of muscle in the carcass increased linearly, 0.022% for each percentage point of including BMB and the percentages of fat and bone had a quadratic response in which adipose tissue has increased until the replacement of 25% and bone tissue decreased to 50% substitution. The ratio of edible portion: bone increased up to 42.5%. As the levels of BMB increased, a decrease in cushion thickness, muscle score and carcass compactness occurred. The shear force of meat was increased by 44kgf for each percentage point of corn replacement. For the physical-chemical composition we observed an increase in the meat mineral matter. The use of BMB in finishing diets for beef cattle reduced the tenderness of the meat, not altering the other qualitative characteristics.