ABSTRACT The objective of this study was to evaluate the effects of polymer coated slow-release urea (SRU) in high-forage diets of beef steers on nutrient intake and digestibility, ruminal fermentation, microbial protein synthesis, and energy balance. Eight 24-mo-old rumen-fistulated castrated Nellore steers (average body weight = 418.0±40.0 kg) were used in a replicated 4 × 4 Latin square design. Animals were randomly distributed to receive one of the following diets: no urea inclusion; 1.0% inclusion of feed grade urea in the diet (dry matter [DM] basis); 1.0% inclusion of slow-release urea 1 in the diet (DM basis); and 1.0% inclusion of slow-release urea 2 in the diet (DM basis). Slow-release urea 2 had a similar composition to that of slow-release urea 1 and differed in that it contained 2.95% sulfur. A high-forage diet was provided (75% of total DM) and corn silage was used as the forage source. Diets with urea had increased crude protein (CP) intake, and CP and total digestible nutrients total tract digestion. Urea sources increased ruminal concentrations of ammonia nitrogen and acetate, and decreased butyrate concentrations. The polymer coated urea did not alter ruminal fermentation when compared with feed grade urea. Diets did not affect the energy balance of steers. Feed grade urea presented greater microbial protein synthesis than polymer coated slow-release urea. The partial replacement of soybean meal by 1% slow-release urea in a diet with 75% forage does not improve ruminal fermentation and microbial protein synthesis, and shows similar results as feeding feed grade urea to beef steers.

ABSTRACTThe objective of this experiment was to quantify the effects of feeding polymer-coated slow-release urea on nutrient intake and total tract digestion, milk yield and composition, nutrient balances, ruminal fermentation, microbial protein synthesis, and blood parameters in dairy cows. Sixteen Holstein cows (580±20 kg of live weight (mean ± standard deviation); 90 to 180 days in milk (DIM); and 28 kg/d of average milk yield) were used in a replicated 4 × 4 Latin square experimental design. The animals were assigned to each square according to milk yield and DIM. The animals were randomly allocated to receive one of the following experimental diets: 1) control (without urea addition); urea (addition of 1% on the diet DM basis); polymer-coated slow release urea 1 (addition of 1% on the diet DM basis); and polymer-coated slow release urea 2 (addition of 1% on the diet DM basis). All diets contained corn silage as forage source and a 50:50 forage:concentrate ratio. Milk and protein yield, production of volatile fatty acids, and propionate decreased when cows were fed diets containing urea. Addition of urea decreased nitrogen efficiency and nitrogen excreted in the feces. However, the diets did not change the cows' microbial protein synthesis, ruminal pH, or ammonia concentration. The inclusion of urea in cow diets decreases milk and protein yield due to lower production of volatile fatty acids. No advantages are observed with supplementation of polymer-coated slow-release urea when compared with feed-grade urea.

This study evaluated the effects of organic and inorganic sources of minerals in diets for mid-lactation dairy cows on milk yield and composition, intake and total apparent digestibility of dry matter and nutrients, blood parameters, microbial protein synthesis, and energy and protein balances. Twenty Holstein cows averaging 146.83±67.34 days in milk and weighing 625.30±80.37 kg were used. The experimental design was a crossover. Diets were composed of corn silage (50%), ground grain corn, and soybean meal, differing with regard to the sources of trace minerals, plus an organic and inorganic mix. The organic mineral source increased milk fat and fat-corrected milk yield without changing milk yield, intake, or total apparent digestibility. Blood parameters, microbial protein synthesis, and energy and protein balances were not affected by the sources of minerals. Organic sources of minerals improve milk fat yield without affecting other parameters.

The objective of this study was to evaluate the influence of unsaturated fatty acids in diets for dairy cows during the transition period and early lactation on intake, digestion and nutrient balance. Thirty-six multiparous and pregnant Holstein cows were randomly distributed to receive one of the experimental diets in the period from 35 days before the expected date of parturition to 84 days post-partum. Diets were fed as a total mixed ration and were as follows: control (C); soybean oil (SO), based on inclusion of 30 g/kg (DM basis); and calcium salts of unsaturated fatty acids (CS), based on inclusion of 30 g/kg (DM basis). Pre-partum dry matter intakes (DMI) of cows fed C, SO and CS were 11.9, 9.5 and 9.6 kg/d, respectively. Post-partum DMI was affected by experimental diets (18.5, 15.0 and 17.4 kg/d for C, SO and CS, respectively). The energy balance in the transition period of animals fed CS was 4.41 Mcal/d higher than cows fed SO and 1.3 Mcal/d higher than cows fed C. Supplementing cows with unsaturated fatty acid sources is a strategy for dairy cows in the transition period.

Objetivou-se com este estudo avaliar os efeitos do uso de diferentes fontes de ácido graxo ômega 6 na dieta de vacas leiteiras no período de transição e início da lactação sobre o desempenho produtivo e bioquímico em vacas da raça Holandesa. As vacas foram alimentadas com as seguintes dietas: 1) controle, 2) óleo de soja refinado, 3) os sais de cálcio de ácidos graxos insaturados (Megalac-E). As dietas foram formuladas para atender às exigências nutricionais das vacas durante o período de pré-parto e pós-parto, dentro de cada grupo experimental. As dietas experimentais afetaram o consumo de matéria seca, o peso corporal, escore de condição corporal e equilíbrio de energia no período pós-parto. As dietas experimentais não afetaram os parâmetros bioquímicos no soro: glicose, proteína total, albumina, uréia, uréia sérica, colesterol total, HDL-colesterol, ácidos graxos não esterificados, β-hidroxibutirato, aspartato aminotransferase, γ-glutamil transferase, fosfatase alcalina, também não sendo observadas diferenças entre os contrastes analisados. As fontes de ácido graxo ômega 6 não influenciaram diretamente o bioquímico de vacas leiteiras no período de transição.

This study aimed to evaluate the effects of using different lipid sources in diets for dairy cows during the transition period and early lactation on productive performance and physiological parameters in Holstein cows. The cows were fed with the following diets: 1) control; 2) Refined soybean oil; 3) Calcium salts of unsaturated fatty acids (Megalac-E). Diets were formulated to meet the nutritional requirements of cows during the pre-partum and postpartum period. The experimental diets affected the dry matter intake, body weight, body condition score, and energy balance in the postpartum period. The experimental diets did not affect the biochemical parameters in serum: glucose, total protein, albumin, urea, serum urea nitrogen, total cholesterol, HDL-cholesterol, non-esterified fatty acids, β-hydroxybutyrate, aspartate aminotransferase, γ-glutamyl transferase, alkaline phosphatase, also not being observed differences between the contrasts analyzed. The lipid sources soybean oil and calcium salts not directly influence the plasmatic physiological parameters of dairy cows in the period transition. But, fat supplementation in the transition period resulted in a better metabolic status and productive performance, mainly improving energy balance post-partum

The objective of this study was to evaluate the utilization of different sources of unsaturated long-chain fatty acids in diets for dairy cows during the transition period and early lactation on the milk fatty acid profile and composition of the protein fraction. Thirty-six Holstein cows were divided into three groups, fed the following diets: control (C); soybean oil (SO); and calcium salts of long-chain unsaturated fatty acids (CS). The milk samples utilized for analysis were obtained weekly from parturition to twelve weeks of lactation; each one of the samples originated from two daily milkings. Milk composition and total nitrogen, non-protein nitrogen and non-casein nitrogen levels were analyzed. The cows receiving the diet with calcium salts had lower concentrations of non-protein nitrogen (%CP) in milk compared with the animals fed the diet with soybean oil. There was a decrease in concentration of medium-chain fatty acids C12-C16, and a concomitant increase in concentrations of long-chain fatty acids >C18 in milk fat for the animals fed the diets CS and SO when compared with diet C. Soybean oil and CS diets increased milk-fat concentrations of the acids C18: 1 trans-11, C18: 2 cis-9, trans-11 and C18: 2 trans-10 cis-12 in relation to diet C. The utilization of sources of long-chain fatty acids in the diet of dairy cows increases the biological value of milk in early lactation due to higher concentrations of specific fatty acids such as CLA C18: 2cis-9, trans-11.

The objective of this study was to determine the effects of dietary energy and recombinant bovine somatotropin (bST) injection to identify genes that might control mammogenesis. Total RNA was extracted from the parenchymal tissue of 32 heifers randomly assigned to one of four treatments: two diets (a standard diet and a high energy, high protein diet), each with or without bST. To perform microarray experiments, RNA samples were pooled (2 animals/pool) before reverse transcription and labeling with Cy3 or Cy5. A 4-node loop design was used to examine the differential gene expression among treatments using a bovine-specific cDNA microarray (National Bovine Functional Genomics Consortium Library, NBFGC) containing 18,263 unique expressed sequence tags (EST). Significance levels of differential gene expression among treatments were assessed using a mixed model approach. Injection of bST altered the expression of 12 % of the genes on NBFGC slide related to tissue development, whereas 6% were altered by diet. Administration of bST increases the expression of genes positively related to cell proliferation and mammary parenchyma to a greater extent than a high energy diet.

Objetivou-se avaliar o uso de fontes de ácidos graxos insaturados nas rações de vacas leiteiras sobre o balanço de nutrientes e o perfil de ácidos graxos do leite. Foram utilizadas 12 vacas Holandesas no terço médio de lactação (média de 128 dias) e (580 ± 20 kg de peso; média ± DP) com produção média de leite de 25kg/dia distribuídas aleatoriamente em três quadrados latinos balanceados 4 x 4 alimentadas com as seguintes dietas: controle (C); óleo de soja refinado; (OS); grão de soja integral (GS) e; sais de cálcio de ácidos graxos insaturados (SCAG). A produção de leite obtida foi de 26,6; 26,4; 24,1 e 25,7kg/dia para as dietas CO, OS, GS e SCAG respectivamente. As vacas alimentadas com a dieta GS produziram menos leite (1,95kg/dia), gordura e lactose em relação às vacas alimentadas com as dietas OS e SCAG. As vacas alimentadas com a dieta SCFA, apresentaram menores concentrações de nitrogênio uréico no sangue, leite, urina (g/dia), maior eficiência do uso de nitrogênio e consumo de energia em relação a dieta OS. As vacas alimentadas com as dietas contendo fontes de ácidos graxos insaturados demonstraram maiores concentrações no leite dos ácidos graxos C18:2 cis-9, trans-11 e C18:1, trans-11, em relação as vacas alimentadas com a dieta CO. O uso de grão de soja integral e óleo de soja promovem maior eficiência dos processos digestivos e aumentam as concentrações de ácidos graxos insaturados no leite de vacas leiteiras.

The objective was to evaluate the effect of unsaturated fatty acid sources supplementation on nutrients balances and milk fatty acid profile of mid lactation dairy cows. Twelve Brazilian Holstein cows in the mid lactation (mean of 128 days) and (580 ± 20kg of weight; mean ± SD) with milk yield of 25kg/d were assigned randomly into three 4 x 4 Latin square, fed the following diets: control (C); refined soybean oil; (SO); whole soybean raw (WS) and; calcium salts of unsaturated fatty acids (CSFA). Milk yield was 26.6; 26.4; 24.1 and 25.7 to the diets CO, SO, WS and CSFA respectively. Cows fed the WS treatment produced less milk (1.95kg/d of milk), fat and lactose than did cows fed the SO and CSFA. Cows fed the CSFA treatment showed less blood, urine (g/d) concentrations of N more energetic efficiency and intake of energy than did cows fed the SO treatment. Cows fed the unsaturated fatty acids sources showed more C18:2 cis-9, trans-11 CLA and trans-C18:1 FA concentration in milk than did cows fed the CO treatment. Diets with whole soybeans and soybeans oil provide more efficient digestive processes, and increase milk composition of unsaturated fatty acids.

Objetivou-se avaliar o balanço de nutrientes e o perfil de ácidos graxos do leite de vacas leiteiras suplementadas com monensina. Doze vacas leiteiras foram distribuídos em 4 quadrados latinos, balanceados 3x3 e alimentados com as três dietas seguintes: controle (C), dieta basal sem adição de monensina; monensina 24 (M24), a adição de 24mg/kg MS de monensina, e monensina 48 (M48), a adição de 48mg/kg de MS. As dietas experimentais influenciaram a eficiência de utilização da energia líquida de lactação. Foi observado efeito quadrático para o balanço energia e nitrogênio. Também foi observado efeito de monensina sobre a produção e composição do leite e no perfil de ácidos graxos do leite. Constatou-se que monensina na dieta de vacas leiteiras, no terço médio de lactação, que usam silagem de milho, melhora o balanço de nutrientes e o perfil de ácidos graxos do leite na dose de 24mg/kg de MS.

The aim of this study was to evaluate the nutrients balance and milk fatty acids profile of dairy cows supplemented with monensin. Twelve Brazilian Holstein dairy cows were distributed into four balanced 3x3 Latin squares, and fed with the following diets: control (C), basal diet without addition of monensin, monensin 24 (M24), addition of 24mg/kg DM of monensin, and monensin 48 (M48), addition of 48mg/kg DM. The experimental diets influenced the efficiency of net energy of lactation utilization. A quadratic effect was observed for the energy balance. It was observed effect of diets on nitrogen balance. It was observed effect of monensin in the milk yield, composition and in the milk fatty acids profile. Monensin in diets of dairy cows in mid lactation, using corn silage, improved the nutrients balance and milk fatty acid profile with 24mg/kg DM.

The objective of this study was to evaluate the effect of lipid and selenium sources in diets for finishing Nellore steers on the fatty acid composition and selenium concentration of the longissimus muscle. Fifty Nellore steers (body weight = 458±39 kg) were assigned to one of six dietary treatments: 1) diet containing sunflower seed and inorganic selenium; 2) sunflower seed and organic selenium; 3) whole cottonseed and inorganic selenium; 4) whole cottonseed and organic selenium; 5) soybeans and inorganic selenium; and 6) soybeans and organic selenium. Diets were formulated with the same amount of nitrogen and calories and supplied once daily to steers in collective pens, with three animals per pen, for 120 d. At the end of the trial, steers were slaughtered and samples of the longissimus muscle were collected for fatty acid and selenium analysis. Effect of selenium sources was detected for selenium concentration in the longissimus muscle. Organic selenium had higher concentrations in the meat compared with inorganic selenium. The total saturated, monounsaturated and polyunsaturated fatty acids did not differ between the sources of lipids and selenium. For selenium sources, no differences were observed between the concentrations of polyunsaturated fat. Also, no differences in C18:2 cis-9 trans-11 concentrations were noted; however, steers fed sunflower seed presented greater proportions of this fatty acid in the meat. The results indicated that the use of sunflower seed, cottonseed or soybeans and organic or inorganic selenium in feedlot diets to Nellore cattle does not alter the great part of the fatty acid profile of the longissimus muscle. However, the inclusion of sunflower seed in the diet increases the meat CLA cis-9, trans-11, which is desirable and beneficial for the health of consumers.

This research was conducted with objective to evaluate the effect of different zinc (Zn) sources and doses in the diet for Santa Ines sheep. Forty lambs at weaning, with 18.4 kg of body weight were supplemented with three different sources of zinc (zinc oxide (ZnO), zinc amino acid and zinc proteinate) and three doses of zinc (200, 400 and 600 mg/kg DM) added to the basal diet. At every 28 days, animals were weighted and blood samples were collected for analyses of zinc (Zn), alkaline phosphatase and immunoglobulin G (IgG) and M (IgM). At the end of experiment, liver samples were collected for determination of the hepatic zinc levels. Zinc was analyzed with atomic absorption spectrophotometer, while phosphatase alkaline and immunoglobulins G and M were analyzed using Laborlab and Bioclin kits, respectively. There was no effect of diets on phosphatase alkaline levels and hepatic zinc, but there was difference in the plasmatic zinc levels and IgG and IgM levels. Based on the accumulation of hepatic zinc, the estimate of the zinc bioavailability, through the regression equation, showed that supplementation with organic and inorganic sources of zinc did not differ in the diet of Santa Ines sheep.

The objective of this study was to evaluate, in Nellore heifers, intake and digestibility of hydrolyzed sugarcane stored for different periods. The experimental design used was a 4 × 4 Latin square, four diets, four Nellore heifers with ruminal cannulas (initial body weight 285.4±23.08 kg and average initial age 14 months) and four periods of 21 days. The diets were composed by fresh sugarcane (time zero) or hydrolyzed sugarcane with addition of 0.5% of hydrated lime, stored for 24, 48 or 72 hours, as the unique forage. Intake and digestibility of feed fractions, nitrogen balance, microbial synthesis efficiency, total number of ruminal protozoans and ammoniacal nitrogen did not significantly change by storing sugarcane with addition of 0.5% of hydrated lime. Sugarcane pH varied quadratically for storage time, with maximum pH of 7.02 after 24 hours from lime addition. Ruminal liquid pH values were higher for heifers fed fresh sugarcane, in comparison with those fed hydrolyzed sugarcane. Sugarcane treated with 0.5% of hydrated lime stored for up to 72 hours does not change ruminal digestion to alter the amount of feed consumed by pubescent Nellore heifers. Thus, lime is a viable technology, once it allows long-duration storage and bee control on treated forage, which contributes to animal feeding logistics.

The objective of this study was to evaluate the fatty acid composition of the longissimus dorsi muscle in carcasses of ¾ Bos taurus taurus ¼ Bos taurus indicus steers fed different sources of fatty acids. Thirty-six steers aged 14 months, with a mean live weight of 320 kg, were fed the following diets for 96 days: 1) control diet, containing no supplemental fat source; 2) CaSFA, diet containing 50 g calcium salts of fatty acids per kg total dry matter; 3) CS diet, containing 210 g cottonseed per kg total dry matter. The fatty acid composition of the longissimus dorsi muscle was determined by gas chromatography. No difference in slaughter weight, carcass weight, backfat thickness, or longissimus dorsi muscle area was observed between animals receiving the diets CaSFA and CS. Animals consuming the two fat-supplemented diets presented higher concentrations of oleic (C18:1), palmitic (C16:0) and stearic (C18:0) acids, corresponding to an average 80.76% of total fatty acids, and higher concentrations of vaccenic acid (C18:1 t11) in the muscle when compared with the control group. Supplementation of the diet of feedlot crossbred steers with CaSFA or cottonseed did not promote significant alterations in the lipid composition of the longissimus dorsi muscle.

The present study was carried out with the objective of evaluating the effects of feeding dairy cows with organic or inorganic sources of zinc (Zn), copper (Cu) and selenium (Se) on blood concentrations of these minerals, blood metabolic profiles, nutrient intake and milk yield and composition. Nineteen Holstein cows were selected and randomly assigned to two groups for receiving organic (n = 9) or inorganic (n = 10) sources of Zn, Cu and Se from 60 days before the expected date of calving to 80 days of lactation. Samples of feed, orts and milk were collected for analysis. Body condition score (BCS) was determined and blood samples were collected for analysis of Zn, Cu and Se concentrations, as well as for metabolic profile. Supplying organic or inorganic sources of Zn, Cu, and Se did not affect dry matter and nutrient intake, blood metabolic profile, milk yield and composition, plasma concentration of these minerals, and BCS or change the BCS in cows from 60 days before the expected date of calving to 80 days of lactation. An effect of time was observed on all feed intake variables, plasma concentrations of Zn and Se, milk yield, milk protein content, BCS and change in BCS.

Objetivou-se com este trabalho avaliar os efeitos de uma dieta de alto nível de energia e proteína combinada com a aplicação de bST no perfil de expressão dos genes da leptina e de seu receptor Ob-Rb no parênquima mamário de novilhas leiteiras. Foram utilizadas amostras de parênquima mamário de 32 novilhas holandesas distribuídas aleatoriamente em quatro tratamentos (n=8): dieta com alto ou baixo teor de energia e proteína combinada ou não com a aplicação de bST. O delineamento utilizado foi em blocos casualizados com arranjo de tratamentos em esquema fatorial 2 × 2. A extração do RNA total das amostras de tecido foi feita e o nível de expressão gênica foi analisado por qRT-PCR utilizando-se o gene da glicuronidase β como controle, pelo método 2-ΔΔCt. Animais que receberam a dieta com alto conteúdo de energia e proteína apresentaram maior expressão de mRNA de leptina, com aumento de 56%, e menor expressão de mRNA do receptor Ob-Rb, com redução de 18%. Por outro lado, a aplicação de bST resultou em diminuição da expressão do mRNA de leptina e do receptor Ob-Rb em 74% e 23%, respectivamente. Não houve interação entre dieta e aplicação de bST. O aumento na expressão de leptina pode explicar, ao menos em parte, os efeitos negativos da dieta de alta energia e proteína, oferecida no período pré-púbere, sobre a produção de leite de novilhas leiteiras.

The objective of this study was to examine the effects of a diet with high level of energy and protein, combined with bST injections, on leptin and leptin-receptor (Ob-Rb) gene expression profile in the mammary parenchyma of dairy heifers. Mammary parenchyma samples from 32 Holstein heifers, randomly assigned to one of four treatments (n=8), were utilized: high or low energy and protein diet, with or without bST injection. The experiment was designed in randomized blocks and arranged in a 2 × 2 factorial arrangement. Total RNA was extracted from tissue samples and gene expression profile was tested in qRT-PCR, against glucuronidase β as a control, using the 2-ΔΔCt method. Animals receiving the diet with high level of energy and protein had higher leptin mRNA expression, with an increase of 56%, and lower leptin receptor Ob-Rb mRNA expression, with a decrease of 18%. On the other hand, bST injection decreased leptin mRNA and receptor Ob-Rb mRNA expression in 74% and 23%, respectively. There was no interaction between diet and bST injection. The increase in leptin expression can explain, at least in part, the detrimental effects caused by diets rich in energy and protein, offered during the prepubertal period, in future milk production of dairy heifers.