Dietas contendo silagem de milho (Zea maiz L.) e feno de capim-Tifton 85 (Cynodon spp.) em diferentes proporções para bovinos.

Avaliaram-se o consumo, a digestibilidade, o pH e concentração de amônia ruminais e a taxa de passagem em bovinos alimentados com dietas contendo feno de capim-tifton 85 (TIF) e silagem de milho (SM) em diferentes proporções. Utilizaram-se quatro animais castrados, com peso médio de 523kg, fistulados no rúmen, distribuídos em um quadrado latino 4 x 4, recebendo 60% de volumoso e 40% de concentrado, na base da matéria seca. O volumoso consistiu das seguintes proporções (%): 100 TIF:0 SM; 67 TIF:33 SM; 33 TIF:67 SM e 0 TIF:100 SM. Os consumos de matéria seca (MS), de matéria orgânica (MO) e de matéria orgânica digestível (MOD), de proteína bruta (PB), de fibra em detergente neutro (FDN) e de carboidratos totais (CHOT) e digeríveis (CHOD) não foram influenciados pelas diferentes proporções de feno de capim-tifton 85: silagem de milho nas dietas, registrando-se valores médios de 9,2; 8,7; 6,4; 1,1; 3,7; 7,3 e 5,4 kg/dia, respectivamente. O consumo de extrato etéreo (EE) elevou linearmente com o aumento da silagem de milho nas dietas. As digestibilidades aparentes da MS, MO, PB, EE e CHO também não foram influenciadas pelas diferentes proporções de silagem de milho, obtendo-se, respectivamente, valores médios de 71,8; 73,0; 69,5; 69,2 e 73,9%. Para a digestibilidade da FDN, observou-se efeito quadrático, estimando-se valor máximo de 65,2% para dietas contendo 30,98% de silagem de milho. Estimou-se concentração máxima de amônia de 12,0 mg/100 ml e valor mínimo de pH de 5,98 às 2,44 e 6,82 horas após a alimentação, respectivamente. A taxa de passagem não foi influenciada pelas diferentes proporções de feno:silagem, no volumoso, apresentando valor médio de 4,2%/hora. Corn silage and Tifton 85 Bermudagrass Hay-Based Diets for Steers. ABSTRACT - The intake, digestibility, ruminal pH and ammonia concentrations and passage rate were evaluated in steers fed corn silage (CS) and Tifton 85 bermudagrass hay (T85H)-based diets, at different forage proportions. Four rumen fistulated steers with 523 kg of live weight were used in a 4x4 latin square design, and fed diets containing 60:40 forage:concentrate proportions in dry matter basis. The forage portion consisted of: 100 T85H:0 CS; 67 T85H:33 CS; 33 T85H:67 CS and 0 T85H:100 CS. The dry matter (DM), organic matter (OM), digestible organic matter (DOM), crude protein (CP), neutral detergent fiber (NDF), total carbohydrates (TC) and total digestible carbohydrates (TDC) intakes were not affected by different T85H: CS proportions and averaged 9.2, 8.7, 6.4, 1.1, 3.7, 7.3 and 5.4 kg/day, respectively. The ethereal extract (EE) intake increased with increasing on corn silage proportion of the diets. The DM, OM, CP, EE and TC apparent digestibilities were not affected by increasing percentage of corn silage on rations and averaged 71.8, 73.0, 69.5, 69.2 and 73,9%, respectively. There was a quadratic effect for NDF digestibility, with maximum value of 65.2% for diets with 30.98% of CS. The N-ammonia maximum content (12.0 mg/100 ml) and minimum value of pH (5.98) were estimated 2.44 and 6.82 hours after feeding, respectively. The passage rate, which was not affected by changing T85H:CS proportions in the forage, averaged 4.2 %/hour

Evaluation of Acid Digestion Procedures to Estimate Mineral Contents in Materials from Animal Trials

Rigorously standardized laboratory protocols are essential for meaningful comparison of data from multiple sites. Considering that interactions of minerals with organic matrices may vary depending on the material nature, there could be peculiar demands for each material with respect to digestion procedure. Acid digestion procedures were evaluated using different nitric to perchloric acid ratios and one- or two-step digestion to estimate the concentration of calcium, phosphorus, magnesium, and zinc in samples of carcass, bone, excreta, concentrate, forage, and feces. Six procedures were evaluated: ratio of nitric to perchloric acid at 2:1, 3:1, and 4:1 v/v in a one- or two-step digestion. There were no direct or interaction effects (p>0.01) of nitric to perchloric acid ratio or number of digestion steps on magnesium and zinc contents. Calcium and phosphorus contents presented a significant (p0.01) calcium or phosphorus contents in carcass, excreta, concentrate, forage, and feces. Number of digestion steps did not affect mineral content (p>0.01). Estimated concentration of calcium, phosphorus, magnesium, and zinc in carcass, excreta, concentrated, forage, and feces samples can be performed using digestion solution of nitric to perchloric acid 4:1 v/v in a one-step digestion. However, samples of bones demand a stronger digestion solution to analyze the mineral contents, which is represented by an increased proportion of perchloric acid, being recommended a digestion solution of nitric to perchloric acid 2:1 v/v in a one-step digestion

Milk fatty acid composition of Holstein x Gyr dairy cows fed sugarcane-based diets containing citrus pulp supplemented with sunflower oil.

Abstract Sugarcane is a strategic roughage source for milk production in the tropics, and its supplementation with plant oils offers great potential for obtaining milk enriched with beneficial fatty acids, such as oleic (cis-9 C18:1), vaccenic (trans-11 C18:1), and rumenic (cis-9, trans-11 CLA) acids. The aim of this study was to evaluate the milk fatty acid composition of cows fed 60% chopped sugarcane-based diets containing citrus pulp and 0.0% (control), 1.5%, 3.0% and 4.5% sunflower oil on a dry matter basis. Twelve multiparous Holstein x Gyr dairy cows with an average milk production of 17±5 kg day-1 and 96±25 days in milk were allocated in a triplicate 4 x 4 Latin square design. There was no effect of dietary treatment on milk production, but sunflower oil supplementation linearly reduced the milk fat content and yield. The milk fat contents of lauric (C12:0), myristic (C14:0), and palmitic (C16:0) fatty acids were linearly reduced with increasing sunflower oil levels. There was a quadratic effect on the milk fat oleic, vaccenic, and rumenic acid contents, while the concentrations of elaidic acid (trans-9 C18:1), trans-10 C18:1 and trans-10, cis-12 CLA linearly increased in response to sunflower oil inclusion. Diet supplementation with sunflower oil linearly reduced both the atherogenicity and thrombogenicity indices and linearly increased the ratio between hypo- and hypercholesterolemic fatty acids in milk fat. The inclusion of up to 4.5% sunflower oil in 60% chopped sugarcane-based diets improved the nutritional quality of milk fat from Holstein x Gyr dairy cows as a result of the increased content of oleic, rumenic and vaccenic acids, which are beneficial to human health, and the concomitant reduction of hypercholesterolemic lauric, myristic and palmitic acids. However, there was an increase in the milk content of trans-10 C18:1 and elaidic acid, which are associated with deleterious effects on cardiovascular health

Ofertas de suplementos múltiplos em tourinhos anelorados na fase de recria, em pastagens durante o período da seca: produção e eficiência microbiana.

O uso de suplementos múltiplos para bovinos visa aumentar o aporte de nutrientes, para melhor atender às exigências nutricionais. Neste contexto, avaliou-se a digestibilidade em tourinhos anelorados em fase de recria, recebendo diferentes ofertas de suplementos em pastagem de Brachiaria decumbens. A área foi dividida em cinco piquetes de 2,0 ha cada. Foram utilizados 30 tourinhos, com peso e idade iniciais médios de 230,0 ±6,14 kg e 8,5 ±0,18 meses, em delineamento inteiramente casualizado, contendo cinco tratamentos, sendo quatro ofertas de suplementos, mais mistura mineral (MM) e seis repetições. Foram avaliados a MM (60g/animal) e suplementos múltiplos, formulados para atender diferentes níveis de suplementação diariamente nas quantidades de 0,5, 1,0, 1,5 e 2,0 kg/animal e suprir 300g/dia de PB. O consumo de suplemento aumentou (P<0,10) a produção de proteína microbiana (PMic), quando comparado com os animais do grupo controle. A produção de PMic apresentou comportamento quadrático com ponto de máxima produção de 404,47 gramas na quantidade de 1,34kg de suplemento. A eficiência de síntese microbiana (EFMic) não diferiu entre os animais do grupo controle e os suplementados. Contudo, observa-se um comportamento quadrático com máxima eficiência 160,38 g/kg de NDT para oferta de 1,18 kg de suplemento. Observa-se que o ponto (1,18 kg) onde ocorreu a máxima EFMic foi inferior ao valor (1,34 kg) em que ocorreu a máxima produção de PMic. Conclui-se que, o ponto ótimo entre produção e eficiência de síntese de proteína microbiana, está entre as ofertas de suplemento diárias de 1,18 e 1,34 kg/animal

Effects of supplements with different protein contents on nutritional performance of grazing cattle during the rainy season

The objective of this study was to evaluate the effects of supplements with different crude protein (CP) contents on grazing cattle intake, digestibility, ruminal fermentation pattern, and nitrogen (N) metabolism characteristics during the rainy season. Five ruminal and abomasal cannulated Holstein×Zebu steers (296 kg body weight, BW) were used in a 5×5 Latin square design. The animals grazed five signal grass paddocks (0.34 ha). The five treatments evaluated were: Control (no supplement) and 1.0 g of supplement/kg BW with 0, 330, 660, and 1,000 g of CP/kg as-fed. The supplement was composed of starch, soybean meal, urea, and ammonium sulphate. There was a positive linear effect (p≤0.033) of the CP content in the supplements on the organic matter (OM), CP, and digested OM intakes. The provision of supplements did not increase (p≥0.158), on average, total and ruminal digestibilities of OM and CP. However, the increase in CP content in the supplements caused a positive linear effect (p≤0.018) on ruminal digestibilities of OM and CP. Additionally, a quadratic effect of the CP contents of the supplements were observed (p = 0.041) for the ruminal digestibility of neutral detergent fiber corrected for ash and protein, with the highest estimate obtained with the CP content of 670 g/kg. The supply of supplements increased (p<0.001) the ruminal ammonia N concentration, which also changed linearly and positively (p<0.001) according to increase in CP content in the supplements. The apparent N balance and relative N balance (g/g N intake) were not, on average, changed (p≥0.164) by the supplements supply. However, both showed a tendency of a linear increase (p≤0.099) with increasing supplement CP content. The supplements increased (p = 0.007) microbial N production in the rumen, which also changed linearly and positively (p = 0.016) with increasing supplement CP content. In conclusion, protein supplementation in grazing cattle during the rainy season, while stimulating voluntary forage intake, results in higher efficiency of N utilization when compared to energy supplementation. This is a possible response to increased microbial protein synthesis in the rumen and improved N status in the animal body

Supplementation levels for growing beef cattle grazing in the dry-rainy transition season.

The objective of this experiment was to study the effects of different levels of supplementation on the performance, intake, digestibility, pH and rumen ammonia concentration in growing bulls grazing Brachiaria decumbens Stapf. pasture, during the dry-rainy transition season. For evaluation of performance, intake and digestibility, it was used 25 non-castrated steers at 11 months of age and initial average body weight of 270 kg, grouped in five plots of five animals each, following a completely randomized design. Each plot received one of the following feeding treatments: mineral mixture and supplement at the proportion of 0.5, 1.0, 1.5 and 2.0 kg/animal/day, corresponding to 0.18, 0.36, 0.54 and 0.72% of the average body weight of the animals. The area designated for the animals was constituted of five 2.0-ha paddocks. For the evaluation of the pH and rumen ammonia concentration, five crossbred non-castrated steers were used, with average body weight of 240 kg, fistulated in the esophagus, rumen and abomasum, disposed in a 5 × 5 Latin square, with five treatments and five experimental periods. Animal performance behaved in a positive linear manner according to the supplementation levels, responding with an increase of more than 80% on weight gains of the animals. Intakes of total and pasture dry matter (DM), organic matter and neutral detergent fiber were not influenced by supplementation. Intakes of crude protein, nonfibrous carbohydrates, ether extract and total digestible nutrients as well as nutrient digestibility and rumen ammonia concentration showed a positive linear pattern in response to supplementation levels. Increasing levels of concentrate supplementation influence positively the performance of bulls growing on pastures during the dry-rainy transition season

Impacts of reduction of phosphorus in finishing diets for Holstein×Zebu steers

In Brazil, commonly males of dairy herd are destined to beef production. However, little is known about the mineral requirements for dairy males. Therefore, the objective of this experiment was to evaluate the calcium (Ca) requirements of Holstein×Zebu steers by determining Ca body tissue concentrations, true absorption and retention coefficients, as well as the requirements for maintenance and weight gain of steers fed diets containing or not containing dicalcium phosphate. Twenty-eight Holstein×Zebu steers with an average initial body weight of 377.5±49.4 kg were utilized. The experiment was conducted as a completely randomized design with a 2×2 factorial arrangement of treatments. Factors included 1) two concentrate levels (30% or 60%); and 2) two levels of dicalcium phosphate (DP), 0 or the amount necessary to attend the estimated dietary requirements. Absorption and retention coefficients, maintenance and gain requirements were estimated. The feedstuffs, refusals, feces, urine, blood and bone were sampled for Ca and phosphorus (P) analysis. Phosphorus intake was improved by the addition of concentrate and presence of DP. There were no variations in the daily fecal and urinary phosphorus excretion as a function of DP. The serum level of inorganic phosphorus was lower in non-supplemented animals, although it was within adequate concentrations for all treatments. Dry matter and organic matter intake, organic matter digestibility, performance, and efficiency were not affected by treatment. Absorption and retention coefficients, and the net requirements for maintenance are similar across treatments. Therefore, the lack of inorganic supplementary Ca and P in diets of feedlot finishing cattle does not change the concentrations of these minerals in bone. The dietary requirements of calcium and phosphorus obtained for cattle were lower than those described by the nutritional requirement systems from Brazil, USA, and UK

Macromineral requirements by beef cattle under pasture supplementation.

The objective of this work was to determine macromineral requirements by Zebu steers grazing Brachiaria decumbens supplemented with concentrate. It was used 24 non-castrated steers, at an average age of 7 months and at initial average weight 180 kg. Eight control animals were slaughtered for determining initial body composition. The 16 remaining animals were divided in four four-animal plots, in a complete random design. Each plot received mineral mixture or supplements at the levels 0.75; 1.50 or 2.25 kg/animal/day. The right half-carcass of eight animals, two per group, was dissected in muscle, fat and bones and all body constituents were weighted for determination of empty body weight and body composition. Net requirements of calcium and phosphorus for an animal at 400 kg body weight were 11.13 g and 5.40 g, respectively. To estimate dietary requirements of maintenance and after, sum them to dietary requirements for gain in order to obtain total dietary requirements, it was adopted endogenous losses and bioavailability present in literature for each mineral macroelement. Total dietary requirement for calcium, phosphorus, magnesium, sodium and potassium for a 400-kg BW animal with 1.0-kg daily weight gain were 34.59; 17.36; 7.82; 5.19 and 41.11 g/day, respectively. Macromineral requirements by beef cattle under pasture supplementation are similar to those recommended by BR-Corte for beef cattle in feedlots