Nine ruminally cannulated cows fed different energy sources were used to evaluate an avian-derived polyclonal antibody preparation (PAP-MV) against the specific ruminal bacteria Streptococcus bovis, Fusobacterium necrophorum, Clostridium aminophilum, Peptostreptococcus anaerobius, and Clostridium sticklandii and monensin (MON) on ruminal fermentation patterns and in vivo digestibility. The experimental design was three 3 × 3 Latin squares distinguished by the main energy source in the diet [dry-ground corn grain (CG), high-moisture corn silage (HMCS), or citrus pulp (CiPu)]. Inside each Latin square, animals received one of the feed additives per period [none (CON), MON, or PAP-MV]. Dry matter intake and ruminal fermentation variables such as pH, total short-chain fatty acids (tSCFA), which included acetate, propionate, and butyrate, as well as lactic acid and NH(3)-N concentration were analyzed in this trial. Total tract DM apparent digestibility and its fractions were estimated using chromic oxide as an external marker. Each experimental period lasted 21 d. Ruminal fluid sampling was carried out on the last day of the period at 0, 2, 4, 6, 8, 10, and 12 h after the morning meal. Ruminal pH was higher (P = 0.006) 4 h postfeeding in MON and PAP-MV groups when compared with CON. Acetate:propionate ratio was greater in PAP-MV compared with MON across sampling times. Polyclonal antibodies did not alter (P > 0.05) tSCFA, molar proportion of acetate and butyrate, or lactic acid and NH(3)-N concentration. Ruminal pH was higher (P = 0.01), 4 h postfeeding in CiPu diets compared with CG and HMCS. There was no interaction between feed additive and energy source (P > 0.05) for any of the digestibility coefficients analyzed. Starch digestibility was less (P = 0.008) in PAP-MV when compared with CON and MON. In relation to energy sources, NDF digestibility was greater (P = 0.007) in CG and CiPu vs. the HMCS diet. The digestibility of ADF was greater (P = 0.002) in CiPu diets followed by CG and HMCS. Feeding PAP-MV or monensin altered ruminal fermentation patterns and digestive function in cows; however, those changes were independent of the main energy source of the diet.

The objective of this study was to investigate the effects of bovine GH1, CAPN1 and CAST gene polymorphisms on carcass and meat traits in Nellore and Nellore x Bos taurus beef cattle. Three hundred animals were genotyped for GH1/MspI (TC/G in intron 3), CAPN316 (AF_252504.2:g.5709C>G) and CAST/RsaI (AY_008267.1:g282C>G) and phenotyped for rib eye area, backfat thickness, intramuscular fat, shear force (SF), and myofibrillar fragmentation index (MFI). No significant associations were observed between the GH1/MspI and CAST/RsaI polymorphisms and phenotypes, although the relation between the CAST/RsaI genotypes and meat tenderness evaluated by MFI approached significant. The fact that the CAPN316 polymorphism did not show adequate segregation in Nellore cattle confirms the difficulty of using this marker in breeding programs of different Bos indicus breeds. However, the positive results of the association analysis obtained for Nellore x B. taurus crosses contributed to the validation of previous findings.

The objective of this study was to evaluate effects of feeding monensin (MON) or a multivalent polyclonal antibody preparation (PAP) against several rumen microorganisms on feedlot performance, carcass characteristics, blood gas profile, and rumenitis of Bos indicus biotype (BT) yearling bulls. The study was designed as a completely randomized design with a 3 × 2 factorial arrangement, replicated 4 times, in which 32 yearling bulls of each of 3 BT evaluated (3-way-cross, TC; Canchim, CC; and Nellore, NE) were fed diets containing either MON at 300 mg·d(-1) or PAP at 10 mL·d(-1) across 3 different periods. No significant (P > 0.10) feed additive (FA) main effects were observed for any of the feedlot performance variables and carcass characteristics with the exception of dressing percentage. Yearling bulls receiving PAP had a decreased (P = 0.047) dressing percentage when compared with yearling bulls receiving MON. Significant (P < 0.05) BT main effects were observed for all feedlot performance variables and carcass characteristics with the exception of kidney-pelvic fat expressed in kilograms (P = 0.49) and LM lipids content (P = 0.45). Crossbred yearling bulls (TC and CC) had greater (P < 0.001) ADG, DMI in kilograms, DMI as % of BW, and improved (P = 0.001) G:F when compared with NE yearling bulls. A tendency (P = 0.072) for a FA main effect was observed for rumenitis scores, in which yearling bulls receiving PAP had lesser rumenitis scores than those receiving MON. When the data were disposed as frequency percentage, 55.6% and 45.7% of the rumens from yearling bulls fed PAP and MON were scored between 0 and 1, respectively (0 = no lesions, 10 = severe lesions). Likewise, a significant BT main effect was observed (P = 0.008), where NE yearling bulls had greater rumenitis scores than those of crossbred yearling bulls (TC and CC). No significant FA main effects were observed (P > 0.10) for any of the fatty acids measured in the subcutaneous adipose tissue, with the exception that yearling bulls receiving MON had greater (P < 0.05) concentrations of palmitic acid (16:0), margaric acid (17:0), docosapentaenoic acid (22:5), and docosahexaenoic acid (22:6) than those yearling bulls receiving PAP. Feeding PAP tended to decrease incidence of rumen lesions and led to similar feedlot performance compared with feeding MON. Thus, PAP is a new technology that presents a possible alternative for ionophores.

RESUMO -Objetivou-se estudar o efeito das diferentes proporções de sangue Simental e Nelore sobre as características da carcaça e da carne de bovinos superprecoces. Foram utilizados 72 bovinos jovens inteiros (18 Nelore; 18 ½ Simental × Nelore;18 Simbrasil e 18 Simental), com 8 meses de idade e 250 kg PV médio inicial. Os animais foram desmamados aos 8 meses de idade em sistema creep-feeding e posteriormente confinados durante 150 dias até atingirem o peso de abate, acima de 465 kg, e abatidos em frigorífico comercial. Os valores de pH e temperatura durante o resfriamento das carcaças foi semelhante para todos os grupos genéticos. Da mesma forma, as variáveis carcaça fria, dianteiro e traseiro, não apresentaram diferenças entre os grupos genéticos. Os cortes foram bastante homogêneos, com excessão do contrafilé e do filé-mignon, que foram maiores nos animais Simental. Os animais da raça Nelore e ½ Simental apresentaram maior força de cisalhamento (4,98 e 4,45 kgf) em relação aos Simental e Simbrasil (3,13 e 3,33 kgf). No entanto, após a maturação da carne durante sete dias, não se constataram diferenças entre os valores de maciez entre os grupos. As perdas por evaporação e gotejamento foram maiores na carne in natura para os animais Simental e Simbrasil, no entanto, aos sete dias de maturação se tornaram semelhantes.O sistema de produção de bovinos superprecoces produz carcaças e cortes semelhantes entre as diferentes raças estudadas. Aos sete dias de maturação, a maciez da carne de animais Nelore foi semelhante à dos demais grupos genéticos utilizados neste estudo.Palavras-chave: cortes comerciais, força de cisalhamento, Nelore, pH, Simental Effect of genetic group on carcass traits and fresh and aged beef tenderness from young cattleABSTRACT -The aim of this work was to study the effect of the different proportions of blood Simmental and Nellore on meat and carcass characteristics of bovine young bulls. Seventy two young bulls were used (18 Nellore; 18 ½ Simmental x Nellore; 18 Simbrasil and 18 Simmental), with medium age of 8 months and with average 250 kg LW initial. The animals were weaned at 8 months of age in system creep-feeding and later confined for 150 days until they reach the slaughter weight above 465 kg and slaughtered in commercial abattoir. The pH values and temperature during carcass cooling was similar for all of the genetic groups. In the same way, the variables cold carcass, forequarter and hindquarter, did not show any differences among the genetic groups. The beef cuts were quite homogeneous, excepting the strip loin and the tenderloin that were larger perceptually for Simmental. The Nellore and ½ Simmental breeds presented larger shear force (4.98 and 4.45 kgf) thanSimmental and Simbrasil (3.13 and 3.33 kgf). However, after the meat ageing for 7 days, no differences were verified among the groups for tenderness values. The losses by evaporation and leaking were higher for non aged Simmental and Simbrasil beef cuts; however, seven days of ageing those losses showed no differences. The syst...

Context The use of two feed additives, to maximise rumen fermentation, in finishing diets offered to feedlot cattle may positively impact performance. Aims This study, conducted at the São Paulo State University feedlot, Botucatu campus, Brazil, was designed to evaluate the effects of the combined use of monensin (MON; 30 mg/kg of dry matter; (DM)) and virginiamycin (VM; 25 mg/kg of DM) in high-concentrate diets during the adaptation and finishing periods on feedlot performance, carcass traits, feeding behaviour, blood gas profile, rumen morphometrics and apparent total tract digestibility of nutrients of Nellore cattle. Methods The experiment was designed as a completely randomised block, replicated six times (3 bulls/pen), in which 72 20 months of age yearling Nellore bulls (388.0 ± 31.1 kg) were fed in 24 pens for 90 days according to the treatments: (1) MON during the entire feeding period (T1), (2) MON + VM during adaptation and only VM during the finishing period (T2), (3) MON + VM during the entire feeding period (T3), and (4) VM during the adaptation and MON + VM during the finishing period (T4). The adaptation program consisted of ad libitum feeding of three diets over the adaptation period of 19 days with concentrate level increasing from 69% to 84% of diet DM. Key results Overall, bulls fed on T2 had a greater DM intake (P &lt; 0.01), final bodyweight (P = 0.04), average daily gain (P = 0.03), hot carcass weight (P &lt; 0.01), final Longissimus muscle area (P = 0.05), Longissimus muscle area daily gain (P = 0.01), improved carcass G:F (P &lt; 0.01) and increased dressing percentage (P &lt; 0.01). Similarly, bulls fed on T2 were faster to consume 1 kg of either DM (P &lt; 0.01) or neutral detergent fibre (P &lt; 0.01) after 60 days on feed. Furthermore, bulls fed on T2 presented a greater (P = 0.05) cell proliferation index in the rumen papillae. Conclusions According to the results, Nellore yearling bulls should be fed high-concentrate diets containing MON and VM during adaptation, and only VM during the finishing period to improve overall feedlot performance. Implications The use of both MON and VM proved to be helpful only during the adaptation period.