Mozart Alves Fonseca

Consumo, digestibilidade e excreção de uréia e derivados de purinas em vacas de diferentes níveis de produção de leite

The objective of this trial was to evaluate the effect of milk production level on intake, digestibility of nutrients, microbial protein synthesis, and nitrogen (N) metabolism in Holstein cows. It was also of particular interest to compare spot urine sampling and total urine collection as methodologies to quantify yield of microbial N using purine derivatives (PD) as indirect microbial markers. Fifteen Holstein cows were grouped by milk yield (5.88 kg/day: LOW treatment; 18.54 kg/day: MEDIUM treatment; and 32.6 kg/day: HIGH treatment) and data analyzed as a completely randomized design. Animals were fed ad libitum corn silage plus one kg of concentrate per each three kg of milk produced. Except for NDF corrected for ash and protein (NDFap), intake of all remaining nutrients was increased by milk yield. Digestibilities of DM and OM and dietary TDN content did not differ among treatments. However, digestibility of CP was higher and that of NDFap was lower on the greatest milk yielding cows (HIGH treatment). Concentrations of milk urea N and serum urea N as well as urinary N excretion were all greatest in the HIGH treatment and were also highly correlated with milk yield. Microbial protein synthesis estimated by PD was lowest on cows in the LOW treatment and did not differ when either spot urine sampling or total urine collection was used. Therefore, spot urine sampling can be used to estimate urinary excretion of nitrogenous compounds and microbial protein synthesis in Holstein cows with different production levels.

Consumo, digestibilidade e excreção de uréia e derivados de purinas em novilhas de diferentes pesos

ABSTRACT - The objective of this trial was to evaluate the effect of body weight (BW) of heifers on intake, apparentdigestibility of nutrients, microbial protein synthesis, ruminal metabolism, and urinary excretion of nitrogenous compounds.The spot urine sampling and the total collection of urine techniques were used to estimate microbial N flow. Twenty-two heiferswith different body weights (523, 453, 315, 235 and 118 kg) were used in a completely randomized design and assigned tothe following treatments: BW523, BW453, BW315, BW235 or BW118. Animals were fed corn silage ad libitum plus 1.5 kg/dayof concentrate on treatments BW523, BW453, BW315 and BW235 and 2 kg/day on BW118 treatment. Intake of nutrientsincreased linearly from treatment BW118 to BW523. However, the opposite was observed when DMI was expressed aspercentage of BW. Digestibilities of DM and OM and dietary TDN did not differ among treatments but digestibilities of CPand NDF corrected for ash and protein (NDF ap ) were greatest and lowest on BW118 treatment, respectively. The urinaryexcretion of urea (mg/kgBW) was higher on BW118 heifers and varied with BW and dietary contents of CP and RDP. Microbialprotein synthesis was not affected by sampling methodology and was lowest on treatment BW118. Therefore, spot urinesampling can be used to estimate urinary excretion of nitrogenous compounds and microbial protein synthesis.Key Words: Holstein, microbial protein, NDFap, serum urea nitrogen, spot sample

Body tissue and chemical component deposition in Nellore bulls, steers and heifers.

The objective on this study was to assess the effects of gender and concentrate allowance level (0.6 and 1.2 % body weight) on body composition and deposition of the main body tissues and chemical components of the empty body weight in Nellore cattle of different gender (bulls, steers and heifers). Thirty five animals were used, fed individually for 112 days, and then slaughtered. A reference group was slaughtered at the beginning of the trial, with average body weight of 338 kg (bulls), 308 kg (steer) and 287.5 kg (heifers). The initial body weight and final slaughter weight of the animals were, respectively, 345.3 and 435.0 kg for the bulls, 328.3 and 396.0 kg for the steer and 303.9 and 372.0 kg for the heifers. The percentage of visceral and subcutaneous fat in the empty body weight was greater in the heifers, although the fat deposition rates were not influenced by gender. The concentrate allowance level did not affect the body composition of Nellore cattle. Bulls had greater and lower protein and fat content, respectively, in the empty body and in the empty body gain than the steers and heifers. The protein deposition rate in the empty body was greater for the bulls compared to the heifers and steers, while the fat deposition rate did not differ among the genders. Gender affects the deposition of carcass and empty body constituents of Nellore cattle.The objective on this study was to assess the effects of gender and concentrate allowance level (0.6 and 1.2 % body weight) on body composition and deposition of the main body tissues and chemical components of the empty body weight in Nellore cattle of different gender (bulls, steers and heifers). Thirty five animals were used, fed individually for 112 days, and then slaughtered. A reference group was slaughtered at the beginning of the trial, with average body weight of 338 kg (bulls), 308 kg (steer) and 287.5 kg (heifers). The initial body weight and final slaughter weight of the animals were, respectively, 345.3 and 435.0 kg for the bulls, 328.3 and 396.0 kg for the steer and 303.9 and 372.0 kg for the heifers. The percentage of visceral and subcutaneous fat in the empty body weight was greater in the heifers, although the fat deposition rates were not influenced by gender. The concentrate allowance level did not affect the body composition of Nellore cattle. Bulls had greater and lower protein and fat content, respectively, in the empty body and in the empty body gain than the steers and heifers. The protein deposition rate in the empty body was greater for the bulls compared to the heifers and steers, while the fat deposition rate did not differ among the genders. Gender affects the deposition of carcass and empty body constituents of Nellore cattle.

Desempenho produtivo de bovinos Nelore de diferentes classes sexuais alimentados com dietas contendo dois níveis de oferta de concentrado

Objetivou-se avaliar os efeitos de classe sexual e nivel de oferta de concentrado sobre o desempenho, o consumo e a digestibilidade dos nutrientes em bovinos Nelore. Trinta e cinco animais, 12 machos inteiros, 11 machos castrados e 12 femeas, provenientes de um mesmo grupo contemporâneo, foram distribuidos aleatoriamente a dois tratamentos, correspondentes aos niveis de oferta de concentrado, 0,6 e 1,2% do peso corporal, respectivamente. Os animais foram alimentados individualmente durante 112 dias, sendo abatidos ao final do experimento, com um grupo referencia abatido ao inicio. Os machos inteiros foram mais eficientes, pois apresentaram maior peso final e de corpo vazio, como resultado da maior taxa de crescimento em relacao as femeas, ficando os machos castrados em posicao intermediaria. Os consumos relativos de materia seca e de todos os demais nutrientes foram superiores nas femeas em relacao aos machos inteiros, de modo que os castrados apresentaram valores intermediarios. As digestibilidades, a excecao do extrato etereo, nao foram afetadas pela classe sexual. As digestibilidades da materia seca e materia orgânica foram superiores para a dieta com nivel de oferta de concentrado de 1,2% do PV. Classe sexual afetou o crescimento e a capacidade de consumo dos animais, porem nao teve efeito sobre a digestibilidade dos nutrientes da dieta. Niveis de oferta de concentrado de 0,6 e 1,2% do PV nao foram suficientes para promover diferencas no desempenho de bovinos Nelore, independentemente de classe sexual.

Síntese de proteína microbiana e concentrações de uréia em vacas alimentadas com diferentes fontes de proteína

Twelve Holstein lactating dairy cows were blocked by days in milk and randomly assigned to three replicated 4 x 4 Latin square to evaluate the effect of different protein sources on efficiency of microbial protein synthesis, concentration of serum (NUS) and milk (MUN) urea nitrogen, and ruminal metabolism. A basal corn silage diet (60% of the total dry matter) was fed plus one of the following proteins sources (DM basis): soybean meal (SBM), cottonseed meal with 38% of crude protein (CSM38), cottonseed meal with 28% of crude protein (CSM28), or soybean meal plus 5% of urea/ammonium sulfate (SBMU). Each experimental period lasted 18 days with 11 days for diet adaptation and seven days for sample collection. Samples of urine and blood were obtained approximately four hours after the morning feeding on day 18 of each period. No significant differences among diets were observed for urinary volume (V), total purine derivatives excretion (PT), microbial CP synthesis and microbial efficiency, expressed in g of CP/kg of TDN intake. In addition, concentration of both NUS and MUN also did not differ among diets. It can be concluded that NUS and MUN as well as microbial CP synthesis and efficiency were not affected by feeding different protein sources to lactating dairy cows.

Uréia em dietas para bovinos: consumo, digestibilidade dos nutrientes, ganho de peso, características de carcaça e produção microbiana

The objective of this trial was to evaluate the effects of replacing soybean meal with urea on performance, carcass traits, and intake and digestibility of nutrients in steers. Microbial protein synthesis and efficiency were also measured in this trial. Sixteen steers averaging 286 kg of BW were assigned to a completely randomized design with a 2x2 factorial approach: two protein sources (soybean meal and urea) and two levels of concentrate (0.75 and 1.25% of BW); four replicates per treatment were used and the experiment lasted 63 days. Diets were isonitrogenous (12% of CP) with the forage portion composed by elephant grass silage and sorghum silage in the ratio of 80:20. Efficiency of microbial protein synthesis was not affected by treatments. Intakes of DM, OM, EE, NDF, NFC and TDN and apparent total tract digestibilities of DM, OM, EE and TDN all increased linearly when the proportion of concentrate was increased in the diet. Except for EE, the protein sources did not affect the intake and digestibility of all remaining nutrients. Feeding high concentrate diets to steers increased energy intake and improved performance. Replacing soybean meal with urea did not change the average daily gain of steers with expected BW gain varying from 1.1 to 1.2 kg/day.

Avaliação de modelos não-lineares e da relação do consumo voluntário de vacas primíparas e de bezerros com a curva de lactação de vacas Nelore

This research was carried out to evaluate five non-linear mathematical models to describe lactation curves of Nelore cows and effect of the cow and calf intake on milk yield. In this study we compared the models of Sikka (1950), Nelder (1966), Wood (1967), Jenkins & Ferrell (1984) and Jenkins & Ferrell (1984) with a fit parameter. Data of production were collected from 12 primiparous cows with a mean live weight of 359 kg (± 8) and its offspring. The milk production was estimated weighing the calf before and after suckling, from birth to 180 days of age. Measurements were made twice a day in a weekly period after 6 hour fasting of liquid and solids. The mathematical models of Sikka, Jenkins & Ferrell, Nelder and Wood failed to describe lactation curve appropriated due to over or underestimation of milk yield peak. Better adjustement was found for the model of Jenkins & Ferrell with a fitting parameter. Cow and calf intake evaluated separately was no correlated with milk yield. Conversely at evaluating both cow and calf together, it was found a positive and a negative correlation with milk yield, respectively. Milk yield is is closely correlated wiht cow and calf intake, and the capacity of the calf to ingest non-dairy solids results in reduction of milk needs from dam.

Níveis de inclusão e tempo de exposição da cana-de-açúcar ao óxido de cálcio sobre parâmetros digestivos e o desempenho de novilhas Nelore

It was evaluated in this work the effects of levels of inclusion and exposure times of sugarcane to calcium oxide on the performance of Nellore heifers, digestibility of dietary components and synthesis of ruminal microbial protein and it was compared titanium dioxide to chromium oxide to estimate the individual intake of concentrate. It was used 30 Nellore females at approximately 24 months of age and average body weight of 285 ± 31 kg and age of 24 months housed in six pens (50 m2 approximately), each one of them with five animals (feeding group). The diets were allocated in a 3 × 2 factorial arrangement, containing three levels of calcium oxide (0; 0.5 and 1.0% of sugarcane fresh matter) and two levels of exposure time (0 and 3 days). There were no effects of calcium oxide exposure time on the intake of microbial nitrogen, dry matter (DM), organic matter (OM), crude protein (CP) and total digestible nutrients (TDN) and daily weight gain, but, it affected the intake of ether extract (EE), neutral detergent fiber corrected for ash and CP contamination (NDFcp), and nonfiber carbohydrate (NFC). The levels of whitewash decreased linearly the intake of OM, NDFap, NFC, and ADG. However, it was not observed effects of the markers (titanium dioxide and chromic oxide) nor interactions among exposure time and level of whitewash on intakes of DM, CP, EE, NDFap, NFC and TDN. Significant interactions between exposure time and level of inclusion of whitewash were observed for total aparent digestibility of DM, OM, and NDF and for content of TDN. Titanium oxide and chromic oxide are equally effective for estimating individual intakes of concentrate by bovine fed in group. Supply of sugar cane stored for three days without whitewash does not change performance of growing heifers.

Níveis de proteína na dieta de bovinos Nelore de três condições sexuais: consumo, digestibilidades total e parcial, produção microbiana e parâmetros ruminais

Twelve Nellore cattle fitted with ruminal and duodenal cannulas were used to investigate the effects of increasing dietary crude protein level (7, 10, 13, and 15%) on intake, ruminal and total tract digestibility of nutrients, microbial protein synthesis, degradabilities of corn silage, corn starch, and cottonseed meal, and ruminal metabolism. Animals were blocked by sexual category (heifers, bulls and steers averaging 254.8, 285.1, and 265.6 kg of body weight, respectively) and then assigned to one out of three Latin squares. Samples were incubated in the rumen of one animal of each sexual category to estimate ingredient degradability after determination of DM, CP and NDF in the incubation residues. Ruminal fluid was collected before and after-feeding to determine pH and concentration of ammonia while ruminal samples for bacterial isolation were taken 6 hours post-feeding. Blood (BUN) and urine (UU) were also collected for measurement of urea concentration. The degradation rates of DM and CP were both lower in corn silage than on corn starch and cottonseed meal. The interaction sexual condition x dietary crude protein level was not significant for nutrient intake. With the exception of EE and NFC, no other significant effect of dietary CP level was observed for daily intake of nutrients. Increasing dietary CP level affected total tract digestibilities of DM, OM, CP, NDF, and NFC and also resulted in higher concentrations of BUN and UU. A significant dietary crude protein level x collection time interaction was observed for ruminal NH3 but not for ruminal pH. It was concluded that increasing dietary CP levels affected intake and total tract digestibility of most nutrients.

Exigências nutricionais de bezerros nelores lactentes

This experiment was carried out to evaluate the nutritional requirements of protein, energy and macro minerals for Nellore calves from birth to 180 days. A total of 20 calves, 10 males (M) and 10 females (F) with average body weight (BW) of 30±3 kg were used. Soon after birth, four (2 males and 2 females) calves were slaughtered to estimate initial body composition of animals that remained in the trial. At 90 days, another eight calves were slaughtered (4 males and 4 females), and the remaining animals were slaughtered at 180 days. Besides milk, the calves were fed with corn silage ad libitum and commercial concentrate set at a maximum of 0.5 kg/animal/day. Two digestibility assay were conducted at 30 and 90 days to estimate the energy intake of the calves. After slaughtered all calves had their right half-carcasses dissected. The content of protein, energy and minerals were estimated by the equation Y = a. EBWb, where EBW is the empty body weight. The relationship EBW/BW of calves was 0.9622 and EBWG/BWG was 0.958, where G is the gain. The net requirements of protein and energy increased with increasing body weight, while calcium decreased. The metabolizable protein requirements for gain of 1 kg BW were 216.96 and 261.98 g for calves with 100 and 200 kg respectively. The following equations are recommended to estimate the body content of preweaning Nellore calves: protein (g/day) = 0.135 × EBW1.0351; energy (Mcal/day) = 1.1798 × EBW1.1805; calcium (g/day) = 0.091 × EBW0.6019; phosphorus (g/day) = 0.00894 × EBW0.9629; sodium (g/day) = 0.00126 × EBW0.9791; magnesium (g/day) = 0.000405 × EBW0.9827; potassium (g/day) = 0.00165 × EBW0.9364.