Growth and yield of cabbage depending on nitrogen ratesThe appropriate program of fertilization for the cabbage crop can be obtained through the synchronization of the plant demand of the plant with the supply of N during the cycle. We determined the influence of rates of nitrogen in the accumulation of dry weight and in the yield, in different phases of the development of cabbage hybrid Shutoku. The experiment was carried out in EPAMIG, Oratorios, Minas Gerais State, Brazil, from July 2 th to October 10 th , 2008. Five rates of N were evaluated (0, 75, 150, 300 and 450 kg ha -1 ). Each treatment was set in randomized block design with four replications. At 50, 64 and 78 days after seeding, the characteristics of growth of the plants, length of the stem, number of leaves, fresh and dry weight of leaves, stems and roots and N content in the dry weight were measured. The harvest occurred at 103 days after seeding. The highest production of cabbage head fresh weight was of 1.13 kg obtained with the rate of 277.8 kg N ha -1 . With the optimal rate of N for the yield, the optimal estimated values for the content of N-NO 3 in leaves and of total nitrogen varied with the sampling time. The initial period of the highest accumulation of dry weight varied with the rates of nitrogen.

The aim of this study was determine the energy and protein requirements for maintenance and gain of Nellore steers. Thirty six Nellore steers with a average weight and age of 359±13 kg and 20 months at the beginning of the trial were individually fed for 56. The steers were fed the same diet (76.43% TDN and 13.62% CP) in three levels of dry matter (DM) intake, ad libitum, 75 g DM/kg BW0.75 and 60 g DM/kg BW0.75. The initial and final body composition was estimated with the marker deuterium oxide that allowed repeated water estimate in the same animal. Deuterium in blood samples was analyzed by mass spectrometry. The effects of intake levels, comparison of intercept and slope among feeding level, and equations were evaluated by the analysis of variance, adopting P<0.05 as a significant level. The net energy for maintenance was 75 kcal/kg EBW0.75 or 70 kcal/kg BW0.75. The net energy for gain for steers with 350 to 450 kg weight was 5.1 to 6.1Mcal. The efficiency of energy utilization for maintenance, km, was 0.7492 and for weight gain, kg, was 0.3404. The metabolizable protein requirement for maintenance was 4.32 * BW0.75 and the net protein for gain was estimated with the equation NPg = (254.68*EBWG) €“ (29.38*RE). The technique of deuterium oxide marker used to estimate energy and protein requirement for maintenance and weight gain at Nellore steers confirm the hypothesis presented in NRC, that NEm is lower than the requirement for taurine cattle. On the other hand, the reverse was true for the NP requirement for maintenance and for weight gain. We consider that indirect method using D2O for estimate body composition in zebu cattle was suitable to determine nutrient requirements.

Thirty-six Nellore steers at 20 months of age on average and initial body weight of 360 kg, fed ad libitum for 78 days and two levels of feed restriction for 58 days and posterior ad libitum feeding for 78 days were used to estimate body composition using the methods of indirect deuterium oxide or the 9 th -10 th -11 th ribs cut. The body water content was calculated with equations established for Nellore steers. The chemical body composition was different for the ether extract content. The animals subjected to feed restriction presented higher body fat content when estimated by deuterium than by the rib cut. The deuterium oxide or 9 th -10 th -11 th ribs cut methods used for body composition determination were effective to estimate body contents for animals fed ad libitum, however, not for animals on feed restriction. Comparatively, the indirect method of deuterium oxide was better than the 9 th -10 th -11 th ribs cut method to estimate body composition in Nellore steers submitted to feed restriction; however, both methods were similar in animals fed ad libitum.