ABSTRACT The objective of this study was to evaluate the effects of different lipid sources in diets for lactating cows on milk yield and composition, conjugated linoleic acid (CLA) content, and fatty acid profile in the milk fat. Five primiparous Holstein cows were distributed in a 5 × 5 Latin square design. Treatments were: control (no lipid addition) and four other diets containing different lipids sources - ground raw soybean, cottonseed, soybean oil, and calcium salts of soybean fatty acids (CSSFA). The greater milk yield (kg/day) and milk lactose (g/kg) and solids non-fat (g/kg) contents were obtained with the animals fed diets with CSSFA. Regarding the fatty acid profile in the milk fat, the diets with CSSFA and ground raw soybeans produced the greatest concentrations of polyunsaturated fatty acids and C182. Supplementation with CSSFA provided a greater production (g/day) of CLA, resulting in almost twice the values shown by the other treatments. The use of different lipid sources does not affect the milk total solids (protein, fat, and lactose) and CSSFA has a positive influence on the fatty acid profile of the milk fat and amount of CLA produced. Additionally, milk yield is not affected by this supplement.

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.

Objetivou-se avaliar níveis de concentrado para bezerros em crescimento. Foram utilizados quatro bezerros mestiços, Holandês × Zebu, com idade média de 7 meses e 155 kg de peso vivo, distribuídos em quadrado latino (4×4). Os animais foram alimentados à vontade, na forma de dieta completa contendo os níveis de 20, 40, 60 e 80% de concentrado, com base na matéria seca (MS). As dietas foram compostas de feno de Cynodon dactylon, fubá de milho, farelo de soja e mistura mineral e foram isoprotéicas (15,4%). Os consumos de MS, matéria orgânica (MO), fibra em detergente neutro (FDN) e carboidratos totais (CT) apresentaram comportamento linear e os consumos de proteína bruta (PB) e nutrientes digestíveis totais (NDT), comportamento quadrático, em kg/dia. Quando calculados em %PV, os consumos de MO, PB, EE e NDT apresentaram comportamento quadrático, enquanto os de MS, FDN e CT tiveram comportamento linear. Os coeficientes de digestibilidade aparente total da MS e PB foram influenciados de forma quadrática pelos níveis de concentrado, enquanto os de MO, EE, FDN e CT tiveram comportamento linear. Não foi observado efeito dos níveis de concentrado sobre a concentração média de nitrogênio amoniacal em cada tempo de análise. Entretanto, para pH, observou-se influência dos níveis nos tempos analisados. Os níveis de concentrado não influenciaram a concentração média de glicose sérica, mas tiveram efeito linear negativo sobre o nitrogênio uréico sérico (NUS) em cada tempo pós-prandial. Pode-se incluir até 60% de concentrado na dieta de bezerros, entretanto níveis maiores podem comprometer a utilização do volumoso.

The objective of this study was to evaluate the levels of concentrate for growing calves. Four Holstein × Brahman crossbred calves with average age of 7 months and 155 kg of body weight were used, distributed into one Latin square design (4 × 4). The animals were fed ad libtum in the form of complete diet containing levels of 20, 40, 60 and 80% of concentrate on the dry matter basis (DM). The diets were composed of Cynodon dactylon hay, corn, soybean meal and mineral mixture, and were isoprotein (15.4%). The DM, organic matter (OM), neutral detergent fiber (NDF) and total carbohydrate (TC) consumption showed linear response; and crude protein (CP) and total digestible nutrients (TDN), quadratic response; expressed in kg/day. When expressed in %BW, the OM, CP, EE and TDN consumption presented quadratic behavior; as DM, NDF and TC showed linear behavior. The apparent total digestibility DM and CP coefficients were quadratic influenced by the levels of concentrate, while OM, EE, NDF and TC showed linear behavior. No effect was observed for the average concentration of ammoniac nitrogen, depending on the levels of concentrate, for each time of analysis. However, for pH, there was influence of the levels for the times analyzed. Likewise, no effect was observed for the average concentration of serum glucose, however, for urea nitrogen serum (UNS), a linear negative effect was observed, depending on the levels for each post-feeding time. Therefore, up to 60% of concentrate could be included in the diet of calves; however higher levels can affect the use of bulky.

Objetivou-se avaliar o efeito da infusão ruminal de ácido propiônico (APR) associado a dietas em mistura completa com duas relações volumoso:concentrado (RVC), 80:20 e 60:40 (% da MS), para novilhos. Foram utilizados quatro novilhos mestiços, Holandês × Zebu, com idade média de 7 meses e 160 kg de peso vivo, distribuídos em delineamento experimental quadrado latino. As dietas foram isoprotéicas e os animais alimentados à vontade, na forma de ração em mistura completa. O ácido propiônico foi produzido por fermentação do soro de leite reconstituído, pelo consórcio das bactérias Enterococcus sp. e Veillonella sp. Diariamente e junto ao fornecimento dos alimentos sólidos, infundiram-se no rúmen 2 L do composto contendo ácido propiônico. Não houve interação APR × RVC para os consumos de nutrientes, exceto nutrientes digestíveis totais (NDT). Os consumos de matéria orgânica (MO), proteína bruta (PB), extrato etéreo (EE), fibra em detergente neutro (FDN) e NDT foram influenciados pela relação volumoso:concentrado utilizada. Não houve interação APR × RVC para as digestibilidades totais de MS, MO, PB, EE, FDN e CT. Todavia, as digestibilidades de MS, MO, EE e CT foram influenciadas pela relação volumoso:concentrado. Não houve interação APR × RVC para as concentrações médias de N-NH3 e pH do líquido ruminal, no entanto, a APR propiciou efeito sobre o pH medido 4 horas após a alimentação. Não se observou interação ou efeito dos fatores principais sobre as concentrações de ácidos graxos voláteis no líquido ruminal, ou níveis de glicose e o nitrogênio uréico sérico.

This study aimed to evaluate the effect of intraruminal infusion of propionic acid (RPA) associated to two (80:20 and 60:40) forage:concentrate ratios (FCR), for young bulls. Four Holstein × Zebu crossbred young bulls with average age of 7 months and 160 kg of body weight (BW) were distributed to a 4 × 4 Latin square design. A total mixed ration, isonitrogenous diets, was ad libitum fed to animals. The propionic acid was obtained by fermentation of reconstituted milk whey by the consortium of bacteria Enterococcus sp. and Veillonella sp.. Daily and along with the supply of solid feeds, 2 L of the compound containing propionic acid were intrainfused in the rumen. There was no RPA × FCR interaction for the intake of nutrients, except for total digestible nutrients (TDN). The organic matter (OM), crude protein (CP), ether extract (EE), neutral detergent fiber (NDF) and TDN intakes were influenced by the FCR. There was no RPA × FCR interaction on the total digestibility of DM, OM, CP, EE, NDF and TC. However, the digestibility of DM, OM, EE and CT were influenced by the FCR. There was no RPA × FCR interaction for the mean N-NH3 concentration and pH of the rumen fluid; however, RPA provided effect on the pH measured 4 hours after meal. There was no interaction or effect of the main factors on volatile fatty acids concentrations in the rumen fluid, or on glucose levels and serum urea nitrogen.