Monensin and a blend of castor oil and cashew nut shell liquid used in a high-concentrate diet abruptly fed to Nellore cattle.

Monensin and functional oils (FO) were supplemented to a high-concentrate diet abruptly fed to 12 ruminally cannulated Zebu steers to study their effects on rumen fermentation, blood metabolites, and , , and relative population. A randomized complete block design with repeated measures over time within 2 experimental periods of 21 d each was used. Treatments were a control (CTR; with no additives), FO (included at 400 mg/kg), and monensin included at 30 mg/kg (M30) or 40 mg/kg (M40). All steers were fed the same high-concentrate basal diet, which consisted of 92.25% concentrate. The first 60 h after transition showed a treatment and hour interaction for ruminal propionate proportion ( = 0.028), and no change in acetate molar proportion ( = 0.633), rumen pH ( = 0.370), and time the rumen pH remained below 5.6 ( = 0.242) were observed. The acetate:propionate ratio decreased ( = 0.020) when monensin was fed in both concentrations (2.30 for the M30 treatment and 2.32 for the M40 treatment) compared with when the CTR was fed (2.85), without being different when the FO (2.71) treatment was fed. Only the M30 treatment did not show pH below 5.2 (P=0.047) over the 60 h after the abrupt transition. Within the entire period, DMI ( = 0.008) and mean ruminal pH ( = 0.040) as well as molar proportions of propionate ( = 0.034) and valerate ( = 0.031) had significant interactions between treatment and day. Total VFA concentration was greater ( = 0.017) for the M30 (117.36 m) and CTR treatments (115.77 m) compared with the M40 treatment (105.02 m), without being different for the FO treatment (111.55 m). Treatments did not change feed behavior parameters. Blood HCO ( = 0.006) and total carbon dioxide ( = 0.003) were greater for the M30 (27.8 and 29.3 mmol/L, respectively) and FO treatments (28.3 and 29.7 mmol/L, respectively) compared with the CTR treatment (25.7 and 26.9 mmol/L, respectively). ( < 0.0001) and ( < 0.0001) decreased their population throughout days, whereas ( = 0.026) increased its population. Independent of ciliated protozoa genera, the greatest ( < 0.0001) protozoa counts were observed for the CTR treatment (52.7 × 10/mL), intermediate for the FO treatment (35.3 x10/mL), and least for steers fed monensin in both concentrations (15 × 10/mL for the M30 treatment and 14 × 10/mL for the M40 treatment). Feed additives had different effects to reduce the subacute acidosis. The use of the FO and M40 treatments did not change most of the rumen fermentation variables, especially in the first week after abrupt transition, when the M30 treatment provided higher protection against acidosis.

Effects of immunocastration and ß-adrenergic agonists on the performance and carcass traits of feedlot finished Nellore cattle.

ß-Adrenergic agonists (ß-AA) are non-hormonal growth promoters which promote muscle hypertrophy in supplemented animals. The effects of two ß-AA in combination with the immunocastration technique on the performance and carcass traits were evaluated using 96 feedlot Nellore males in a randomized complete block design with two sex conditions (immunocastrated (IC) v. non-castrated (NC)) and three treatments: CON (no ß-agonists added), RH (300 mg of ractopamine hydrochloride/day, for 33 days) or ZH (80 mg of zilpaterol·hydrochloride animal/day for 30 days, removed 3 days for required withdrawal period). The trial was carried for 100 days where in the first 70 days animals did not receive ß-AA (phase 1) and during the last 30 days they were treated with ß-AA (phase 2). The performance and ultrasound measurements of longissimus muscle area (LMA), backfat thickness (BFT) and rump fat thickness (RFT) were evaluated in both phases. No sex condition v. treatment interactions were observed for any trait. The NC animals had higher average daily gain (ADG) and final BW than the IC animals, but they did not differ in dry matter intake (DMI) and feed efficiency (gain to feed). The NC animals showed greater LMA (P=0.0001) and hot carcass weight (P=0.0006), and smaller BFT (P=0.0007), RFT (P=0.0039) and percentage of kidney, pelvic and heart fat (P<0.0001) when compared with IC animals. The animals fed ZH showed greater ADG (P=0.0002), G : F (P<0.0001) and dressing per cent (P=0.0136) than those fed RH and CON diets. No differences in BW and DMI were observed. A interaction between treatment and time on feed was observed for LMA and BFT, in which the animals fed ZH diet showed greater LMA (P<0.01) and lower BFT (P<0.01) at 100 days than the animals fed RH and CON diets, whereas RH and CON diets did not differ. Immunocastration decreases muscle development and increases carcass finishing. In contrast, ß-AA increases muscle and decreases fat deposition. The ZH has a higher action on the muscle metabolism than animals fed RH diet. However, RH diet achieves a better balance because it has an intermediary performance between non-supplemented and ZH animals and does not decrease the carcass fat.

Exigências líquidas de energia e proteína de tourinhos Santa Gertrudes confinados, recebendo alto concentrado / Energy and protein requirements of Santa Gertrudis young bulls in feedlot, fed high concentrate diets

Com o objetivo de determinar as exigências de energia e proteína para ganho de tourinhos Santa Gertrudes, 33 tourinhos, com idade de 12 meses e peso inicial médio de 314,6±33,2kg, foram confinados durante 115 dias, após 56 dias de adaptação. Seis animais foram abatidos após adaptação, para determinação da composição química corporal inicial. Os animais receberam dietas contendo 80% de concentrado, avaliando-se a inclusão de 0; 4,5; e 9,0% do subproduto concentrado da produção de lisina na matéria seca. As exigências de energia líquida de ganho (ELg) foram estimadas em função do peso de corpo vazio (PCVZ) e do ganho de PCVZ (GPCVZ), e as exigências líquidas de proteína para ganho (PLg) foram estimadas em função do GPCVZ e da energia retida (ER). As equações obtidas para ELg e PLg foram: ELg (Mcal/dia) = 0,0061×PCVZ0,75×GPCVZ0,578; e PLg (g/dia) = 208,1×GPCVZ - 1,0868×ER. A exigência de energia líquida encontrada para ganho de 1kg de PV foi de 3,93; 4,88 e 5,76Mcal, e a exigência de proteína metabolizável foi de 367,81; 393,59 e 391,63g, respectivamente, para animais com 300, 400 e 500kg de peso corporal. O valor de exigência líquida para mantença foi obtido por meio da regressão do logaritmo da produção de calor (PC), em função da ingestão de energia metabolizável, chegando-se ao valor de 75,6kcal/PVz0,75/dia. Concluiu-se que, devido ao aumento do teor de gordura na composição do ganho, animais de maior peso de corpo vazio apresentam maiores exigências líquidas de energia.

The objective of this study was to determine the energy and protein requirements for gain of Santa Gertrudis young bulls. Thirty-three 12-month-year-old animals, with initial body weight of 314.6±33.2kg, were kept in individual pens during 115 days, after 56 days of adaptation. Six animals were slaughtered after adaptation and determined the chemical composition of initial body. The concentrate proportion in the diet was 80%, on dry matter basis, and the levels of LPB studied were: 0, 4.5 or 9.0%. It was verified that the net energy requirement observed for weight gain of 1kg was 3.93, 4.88 and 5.76Mcal, and the metabolizable protein requirement was 367.81, 393.59 and 391.63g, respectively, for animals with 300, 400 and 500kg of body weight. The estimated maintenance energy requirement observed was 75.6kcal/LW0.75/day. The conclusion was thatbecause of the fat content in the gain composition, animalswith higher EBW have higher net energy requirements.

Carcass quality of feedlot finished steers fed yeast, monensin, and the association of both additives / Qualidade de carcaça de novilhos terminados com dietas contendo levedura, monensina e associação de ambos aditivos

To evaluate the effects of the supplementation of feed additives on carcass quality in beef cattle, 72 Nellore steers (339.5kg, 20-month old) were feedlot finished and fed for 91 days one of the following diets: 1) control with no additives; or added of 2) live yeast culture; 3) monensin; or 4) the association of both additives. After slaughter, renal, pelvic, and inguinal fat and hot carcass weights were recorded and carcass was split into muscle, bone, and trimmable fat. Carcass Longissimus muscle area and subcutaneous fat thickness at the 12th rib were measured and steaks of Longisimus muscle were taken to determine meat color, shear force, drip, and cooking losses. Yeast increased carcass dressing percentage but there were no effects on hot carcass weight, Longissimus area, subcutaneous fat thickness, percentage and weight of retail cut yield and trimmings. Feed additives had no effect on carcass pH, meat color, fat content, shear force, and drip losses. Supplementation of yeast, monensin or the association of both additives had no important effects on carcass traits and on meat quality of feedlot finished steers.

Avaliaram-se os efeitos da suplementação de aditivos alimentares sobre a qualidade de carcaça em bovinos de corte. Usaram-se 72 novilhos Nelore com média de peso de 339,5kg e 20 meses de idade, terminados em confinamento e alimentados por 91 dias com uma das quatro dietas: 1) dieta controle sem aditivos, ou com a adição de 2) leveduras vivas, 3) monensina ou 4) associação entre ambos aditivos. Após o abate, os pesos da gordura renal, pélvica e inguinal e da carcaça foram medidos e a carcaça dividida em músculos, ossos e aparas. Foram mensurados a área de olho de lombo e a espessura de gordura subcutânea sobre o músculo Longissimus na região da 12ª costela e foram obtidos bifes para a determinação da cor, força de cisalhamento e perdas por cocção e cozimento da carne. A levedura aumentou o rendimento de carcaça, mas não houve efeito dos tratamentos sobre o peso de carcaça, porção comestível e aparas. Os aditivos não influenciaram o pH da carcaça, a cor, a gordura intramuscular, a força de cisalhamento e as perdas por exsudação da carne. A suplementação, com levedura e com monensina em associação ou separadamente, não teve efeito importante sobre a qualidade da carcaça em novilhos terminados em confinamento.

Digestibilidade aparente de dietas com níveis crescentes de concentrado em novilhos Brangus e Nelore / Apparent digestibility of diets with increasing concentrate levels in Brangus and Nellore steers

Determinou-se a digestibilidade aparente, pela coleta total de fezes, de dietas contendo 20, 40, 60 ou 80 por cento de concentrado para novilhos Brangus e Nelore. Oito animais, quatro de cada raça, foram utilizados em delineamento quadrado latino 4x4, com cinco dias de adaptação e cinco dias de coleta de fezes, em cada período. A idade e o peso iniciais dos Brangus e Nelore foram 13 meses e 248kg e 30 meses e 403kg, respectivamente. Houve efeito do nível de concentrado (P<0,01) sobre os coeficientes de digestibilidade da matéria seca (MS), proteína bruta (PB), extrato etéreo, fibra bruta, fibra em detergente neutro, extrativo não-nitrogenado (ENN), matéria orgânica (MO) e nutrientes digestíveis totais (NDT). A dieta com 80 por cento de concentrado apresentou maior digestibilidade da MS, PB e NDT. A digestibilidade do ENN e da MO e a ingestão de MS foram diferentes entre raças (P<0,05); os Brangus tiveram maior ingestão de MS e NDT (P<0,01). Houve interação entre raças e níveis de concentrado quanto à ingestão de MS e NDT (P<0,01), com maior ingestão pelos Brangus, nos níveis mais altos de NDT. Os Nelore foram menos adaptados às dietas ricas em concentrado em relação aos Brangus.

The apparent digestibility of diets with 20, 40, 60 or 80 percent of concentrate fed Brangus and Nellore steers was determined through total fecal collection. Eight animals, four of each breed, were used in two 4 x 4 Latin square design with five days of adaptation to the diets and five days of collection in each period. The initial age and body weight of Brangus and Nellore steers were 13 months and 248 kg, and 30 months and 403kg, respectively. Concentrate levels affected (P<0.01) the digestibility coefficients of dry matter (DM), crude protein (CP), ether extract, crude fiber, neutral detergent fiber, nitrogen free extract (NFE), organic matter (OM) and total digestible nutrients (TDN). The diet with 80 percent of concentrate showed higher DM, CP and TDN digestibilities. The digestibility of NFE, OM and the dry matter intake were different according to the breeds (P<0.05). Brangus showed higher DM and TDN intake. The DM and TDN intake showed interaction (P<0.01) breed by concentrate level, with higher intake for the Brangus at higher TDN diets. The Nellore steers were less adapted to diets rich in concentrate than Brangus steers.