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Crossbreeding has been used to improve performance in beef cattle, however the effects of breed composition on methane (CH4) production, yield and intensity from cattle raised in tropical intensive and integrated systems remain unknown. To assess the impact of breed composition on performance and methane emissions, Nellore (NEL; yr 1: BW = 171.5 ± 19.4 kg; n = 10; yr 2: BW = 215.8 ± 32.3 kg, n = 25) and Angus x Nellore crossbred (AN; yr 1: BW = 214.2 ± 26.4 kg, n = 10; yr 2: BW = 242.5 ± 32.2 kg, n = 25) were compared. The animals grazed on integrated crop-livestock system in the growing phase (stocking rate 2452 kg BW/ha, herbage mass 4,884 kg dry matter (DM)/ha, forage allowance 5.9 kg DM/100kg BW) and then were finished in a feedlot. Steers (n = 8) from each breed composition were randomly selected in each phase to measure CH4 production using a sulfur hexafluoride (SF6) tracer technique and DM intake (DMI) using titanium dioxide. Compared with NEL, AN had both superior total gain and average daily gain (ADG) in the grazing period. The AN presented greater ADG in the feedlot with a shorter finishing period and resulted in greater carcass yield and carcass ADG. Methane production (kg/period) was lower in NEL (19% less) than AN in grazing (P<0.01), and no difference was observed in feedlot. The NEL had less CH4 intensity (CH4/BW) in grazing but greater CH4 per unit of ADG in the feedlot compared to AN. Breed composition did not influence the CH4 yield (CH4/DMI) in either phase, despite the difference in feedlot DMI (kg/day). In conclusion, crossbreeding may be an option to improve performance and reduce the CH4 per ADG in tropical climate conditions, resulting in lower methane emission per kg of meat produced.

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The aim of this study was to evaluate the consumption, performance, feed efficiency, glucose concentration, and the cost per kilogram of weight gain of crossbred Holstein-Gyr heifers (n = 33) subjected to one of the three waste milk step-down strategies: 6L-30d/4L-60d/2L-90d (T1), 6L-45d/4L-60d/2L-90d (T2), and 8L-30d/6L-60d/3L-90d (T3). Heifers were weaned at the age of 91 days. Water and starter were provided ad libitum. The average waste milk intake was higher in T3 than in T1 and T2 strategies until 30 days and between 60 and 90 days. The starter intake did not differ among the strategies until 45 days, but it was higher in strategy T1 than in strategy T3 between 60 and 90 days. The waste milk step-down strategy did not influence the total dry matter intake, average daily gain, body weight, and feed efficiency. Glucose concentrations in plasma varied within a range that could be considered normal and were similar among the treatments. The average cost per kilogram of weight gain was the lowest in strategy T1 (US$3.0) compared to that in the other strategies (T2, US$3.2, and T3, US$3.6). The 6L-30d/4L-60d/2L-90d waste milk step-down strategy was the most effective, since it increased the starter intake, led to normal glucose concentrations in plasma, and caused similar weight gain compared with the other strategies; however, it had a lower cost per kilogram.

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RESUMO

Com a crescente demanda do mercado por carne bovina de qualidade,proveniente de animais criados a pasto,aliada à exigência da erradicação e confirmação de área livre de febre aftosa,o Brasil passa a ter um amplo mercado a conquistar. Para se obter o animal de qualidade e precoce, novas tecnologias devem ser adotadas para a viabilização dessa pecuária moderna e de ciclo curto.

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RESUMO

Com a crescente demanda do mercado por carne bovina de qualidade,proveniente de animais criados a pasto,aliada à exigência da erradicação e confirmação de área livre de febre aftosa,o Brasil passa a ter um amplo mercado a conquistar. Para se obter o animal de qualidade e precoce, novas tecnologias devem ser adotadas para a viabilização dessa pecuária moderna e de ciclo curto.

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RESUMO

Background: Chromium (Cr) is an essential nutrient for both humans and animals. Cr can be found in different sources, both organic and inorganic. In general, the organic forms of Cr are better absorbed than the inorganic forms. The metabolic effects of Cr are affected by the ingested formulation of this element. Several studies have shown that diet supplementation with Cr improves the growth rate, feeding efficiency and carcass composition of land animals, but the nutritional value of Cr to fish is scarcely known. The aim of the present study was to compare two forms of chromium (chelate and yeast) supplemented in the diets of Nile tilapia (Oreochromis niloticus) at different concentrations and their effect on productive performance, blood parameters and the liver concentrations of cholesterol and triglycerides.Materials, Methods & Results: Nine groups with 36 Nile tilapia fish were formed: a control group, four groups supplemented with chromium (Cr) chelate (8.0 ppm, 16.0 ppm, 24.0 ppm, and 32.0 ppm) and four groups supplemented with chromium yeast (0.8 ppm, 1.6 ppm 2.54 ppm, and 3.2 ppm) for six weeks. After this period, the performance of the fish (weight gain, consumption, food conversion and filet yields), blood parameters (glucose, triglycerides, total protein, total cholesterol, HDL, LDL, and VLDL) and liver cholesterol and triglyceride concentrations were measured. dietary supplementation with chromium chelate (8.0 ppm, 16.0 ppm, 24.0 ppm, and 32.0 ppm) and four levels of chromium yeast (0.8 ppm, 1.6 ppm 2.54 ppm, and 3.2 ppm) did not influence the productive performance, filet yield, blood glucose, triglycerides, total protein, total cholesterol, or lipoprotein or the hepatic levels of triglycerides in Nile tilapia. However, the hepatic cholesterol levels were reduced in tilapia supplemented with 3.2 g/kg Cr yeast (2.85 ppm of total Cr in diet), although hepatic triglycerides were not affected.[...]

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Background: Chromium (Cr) is an essential nutrient for both humans and animals. Cr can be found in different sources, both organic and inorganic. In general, the organic forms of Cr are better absorbed than the inorganic forms. The metabolic effects of Cr are affected by the ingested formulation of this element. Several studies have shown that diet supplementation with Cr improves the growth rate, feeding efficiency and carcass composition of land animals, but the nutritional value of Cr to fish is scarcely known. The aim of the present study was to compare two forms of chromium (chelate and yeast) supplemented in the diets of Nile tilapia (Oreochromis niloticus) at different concentrations and their effect on productive performance, blood parameters and the liver concentrations of cholesterol and triglycerides.Materials, Methods & Results: Nine groups with 36 Nile tilapia fish were formed: a control group, four groups supplemented with chromium (Cr) chelate (8.0 ppm, 16.0 ppm, 24.0 ppm, and 32.0 ppm) and four groups supplemented with chromium yeast (0.8 ppm, 1.6 ppm 2.54 ppm, and 3.2 ppm) for six weeks. After this period, the performance of the fish (weight gain, consumption, food conversion and filet yields), blood parameters (glucose, triglycerides, total protein, total cholesterol, HDL, LDL, and VLDL) and liver cholesterol and triglyceride concentrations were measured. dietary supplementation with chromium chelate (8.0 ppm, 16.0 ppm, 24.0 ppm, and 32.0 ppm) and four levels of chromium yeast (0.8 ppm, 1.6 ppm 2.54 ppm, and 3.2 ppm) did not influence the productive performance, filet yield, blood glucose, triglycerides, total protein, total cholesterol, or lipoprotein or the hepatic levels of triglycerides in Nile tilapia. However, the hepatic cholesterol levels were reduced in tilapia supplemented with 3.2 g/kg Cr yeast (2.85 ppm of total Cr in diet), although hepatic triglycerides were not affected.[...](AU)

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This research had as an objective to analyze the profitability of the activity of beef cattle finished in confinement. Specifically, it was also intended to evaluate the effect of scale of production and price variations throughout the year on profitability, and identify the components of the total and operational effective costs that exercised higher representativeness on the production of 15 kg and to estimate the equilibrium point. The data collection took place from January, 2008 to December, 2009, in a production system of beef cattle finished in confinement, located in the municipal district of Sete Lagoas-MG. The profitability analysis was carried out by the Custo Bovino Corte® software, considering the gross and the liquid margin and the result (profit or loss) as indicators of economical efficiency. The gross and the liquid margins, and the result were positive in 2008, indicating that the production system has survival conditions over short, medium and long terms with consequent capitalization. In 2009, for presenting positive gross and liquid margins, the activity has survival conditions over short and medium terms; but, because of the negative results, this production system does not have survival conditions over long term because the farmer is decapitalizing itself. The components of total cost and total operational costs that exercised higher influence on the production of 15 kg were: animal acquisition, feeding and labor.

Esta pesquisa teve como objetivo analisar a rentabilidade da atividade de bovinos de corte terminados em confinamento. Pretendeu-se, ainda, avaliar o efeito da escala de produção e a variação de preços, ao longo do ano, bem como identificar os componentes do custo total e operacional efetivo que exerceram maiores representatividades na produção da arroba de carne e estimar o ponto de equilíbrio. A coleta de dados foi de janeiro de 2008 a dezembro de 2009, em um sistema de produção de bovinos de corte terminados em confinamento, localizado no município de Sete Lagoas MG. A análise de rentabilidade foi realizada utilizando o software Custo Bovino Corte®, considerando a margem bruta, a margem líquida e o resultado (lucro ou prejuízo) como indicadores de eficiência econômica. As margens bruta, líquida e o resultado foram positivos no ano de 2008, evidenciando que o sistema de produção tem condições de sobreviver a curto, médio e longo prazos, com consequente capitalização. Para o ano de 2009, por obter margens bruta e líquida positivas, a atividade tem condições de sobreviver a curto e médio prazos; mas, pelo resultado ter sido negativo, esse sistema de produção não tem condições de se manter a longo prazo, pois o pecuarista está se descapitalizando. Os componentes do custo total e custo operacional total que exerceram maiores representatividades na produção da arroba de carne foram, em ordem decrescente, aquisição de animais, alimentação e mão-de-obra.

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