RESUMO O presente trabalho avaliou a produção e a composição do leite de vacas leiteiras alimentadas com níveis crescentes de castanha de caju na porção concentrada da dieta. Foram utilizadas oito vacas holandesas multíparas, entre a terceira e a quinta lactação, com produção média de 28,0 ? 4,0 kg de leite dia-1, dispostas em delineamento experimental quadrado latino 4 x 4, duplo. As dietas avaliadas consistiram na inclusão de diferentes níveis de castanha de caju moída (CC): 0; 80; 160 e 240 g kg-1 na porção concentrada, possibilitando concentrações de extrato etéreo de 31,6; 46,0; 68,9 e 73,1 g kg-1 na matéria seca da dieta, respectivamente. A silagem de milho foi utilizada como volumoso único, na proporção 50% e as dietas foram formuladas para serem isoproteicas. A dieta foi fornecida na forma de mistura total. A produção média de leite foi 30,3 kg dia-1. As concentrações de proteína, N-ureico e lactose não apresentaram variações significativas (p>0,05) entre as dietas. A inclusão de 24% de castanha de caju na porção concentrada da dieta, mantem a produção de leite, reduz o conteúdo de gordura no leite e juntamente com a redução na concentração de ácidos graxos de cadeia curta e o aumento nas concentrações de ácidos graxos de cadeia longa, proporciona maior valor nutracêutico ao leite, tornando a utilização de castanha excelente alternativa para obtenção de leite com maior benefício à saúde humana.

ABSTRACT This work evaluated the production and composition of milk from dairy cows fed increasing levels of cashew nuts in the concentrate portion of the diet. Eight Holstein multiparous cows were used, between the third and fifth lactation, with an average milk yield of 28.0 ? 4.0 kg day-1, arranged in a double 4 x 4 Latin square experimental design. The assessed diets consisted of including different amounts of ground cashew nuts (CN): 0; 80; 160 and 240 g kg-1 of concentrate portion, which resulted in ether extract contents of 31.6; 46.0; 68.9 and 73.1 g kg-1 of dietary dry matter, respectively. Corn silage was used as the only roughage at a proportion of 50% and diets were formulated to be isoprotein. Diet was offered as a complete mixture. Average milk yield was 30.3 kg day-1. The concentration of protein, N-urea and lactose did not present significant variations (p>0.05) among the diets. The inclusion of 24% of cashew nut in the concentrate portion of the diet, maintains milk production, reduces milk fat content and together with the reduction in the concentration of short chain fatty acids and the increase in the concentrations of long chain fatty acids, provide a greater nutraceutical value to milk, making the use of cashew nut an excellent alternative for obtaining milk with more benefits to human health.

ABSTRACT This study aimed to evaluate the effect of diets containing sunflower or corn silages and concentrate based on citrus pulp or ground corn on intake, apparent digestibility, feeding behavior, microbial protein production, and production, composition, and fatty acid profile of milk from dairy cows. Eight multiparous lactating Holstein cows (586±61 kg live weight; 25.0±4.0 kg daily milk yield at 80 to 120 days in milk) were randomly assigned to a double 4 × 4 Latin square design with a 2 × 2 factorial array. The experimental diets were: sunflower silage + citrus pulp-based concentrate; sunflower silage + ground corn-based concentrate; corn silage + citrus pulp-based concentrate; and corn silage + ground corn-based concentrate. The dry matter intake was highest for diets containing sunflower silage and lowest for diets with citrus pulp. Sunflower silage provided the highest intakes of crude protein, neutral detergent fiber, and ether extract. Except for the ether extract, the type of forage and carbohydrate did not influence the apparent nutrient digestibility. The forage and carbohydrate sources did not influence the feed eating time, but animals fed sunflower silage showed decreased rumination time and chewing activity. The microbial protein production was not altered with the diets. No differences were observed for milk production or composition, except for the milk urea nitrogen and lactose concentration. The type of forage influenced the milk fatty acid profile, to which corn silage presented higher values for fatty acids up to a 17-carbon chain length. The inclusion of sunflower silage and citrus pulp, compared with corn silage and ground corn, alters dry matter intake and ingestive behavior, but maintains milk production and composition with satisfactory characteristics of the milk fatty acid profile, providing an alternative feed for dairy cows.

Resumo Conduziu-se este trabalho com o objetivo de avaliar os efeitos da substituição do milho por polpa cítrica sobre o desempenho de vacas leiteiras. Utilizaram-se nove vacas (três canuladas no rúmen) da raça Holandesa, pluríparas, com 80 ± 24 dias de lactação e produção média diária de 20 ± 0,58 kg de leite. Os animais foram confinados em tie stall, com cocho e bebedouro individuais. Utilizou-se um quadrado latino 3 x 3. Os períodos experimentais tiveram duração de 21 dias, sendo 14 de adaptação e sete de coleta. Os tratamentos foram constituídos de 100% milho grão (MG), 50% milho grão e 50% polpa cítrica (MP) e 100% polpa cítrica (PC). Não houve diferenças significativas na ingestão dos nutrientes (MS, MO, FDN, FDA, PB, amido) entre dietas. O tratamento com polpa cítrica produziu maior proporção de acetato em relação aos demais, bem como maior relação acetato/propionato. As médias de pH situaram-se entre 5,86 e 7,35. As médias de N-NH3 apresentaram maiores diferenças nos tempos 2 e 3 horas pós-alimentação. Não houve diferenças entre as dietas para produção total de leite corrigido para 4% de gordura, proteína, lactose, extrato seco total (EST) e nitrogênio uréico do leite (NUL).

Abstract The objective of this research was to evaluate the effects of replacing corn grain by citrus pulp on dairy cows performance. Nine Holstein cows (three cannulated in the rumen), at 80 ± 24 milking days, and daily medium production of 20 ± 0.58 kg/day were used. Animals were maintained in tie stall with individual feeder and drinker. Experimental design was a 3 x 3 Latin square. Experiment lasted 21 days, being 14 days of adaptation and seven of collection. Treatments were 100% corn grain (CG); 50% corn grain and 50% citric pulp (CG-P) or 100% citrus pulp (P). There were no differences in nutrients (DM, OM, NDF, ADF, CP, starch) ingestion among diets. The treatment with citrus pulp produced larger proportion of acetate in relation to the others, as well as larger acetate/propionate ratio. The pH averages ranged between 5.86 and 7.35. The averages of N-NH3 presented larger differences in the times 2 and 3 hours after feeding. There were no differences among the diets for total 4%-fat corrected milk production, protein, lactose, total dry extract (TDE) and milk urea nitrogen (MUN).

The objective of this study was to evaluate the effects of genetic group and environmental factors, including farm of origin, season of calving and lactation number, on the individual lactation curves of 1,010 Holstein-Gyr, Guzerat-Holstein, Holstein-Nellore, and Holstein-Zebu F1 cows on the experimental farms of the Agricultural Research Company in Minas Gerais (Empresa de Pesquisa Agropecuária de Minas Gerais, EPAMIG). Least squares analysis and the incomplete gamma function were used to investigate differences in early milk yield, peak milk yield, time from onset to the lactation peak, persistency, total milk yield and lactation duration. The highest early yields were observed for Holstein-Gyr and Holstein-Zebu, and the lowest were observed for Holstein-Nellore cows. Early yield increased with lactation number, and the lactations that began in the late rainy and early dry seasons had the highest early yield. The time between lactation onset and the lactation peak was longer for primiparous Holstein-Gyr and Holstein-Guzerat cows. The lowest yields at the lactation peak were observed for the first lactation number. The highest values of persistency were observed for the first lactation number in Holstein-Guzerat cows. Total production from Holstein-Gyr and Holstein-Zebu cows were higher by approximately 14% and 29% compared with Holstein-Guzerat and Holstein-Nellore cows, respectively. The highest total yields were observed in lactations beginning in the dry season. Total yield increased with lactation number. The shortest lactation periods were observed in lactations beginning late in the rainy season. The incomplete gamma function was used to fit the individual curves from the genetic groups evaluated. The total yield differences were linked to early yields and yields at the peak of lactation.

Objetivou-se com este trabalho avaliar os efeitos de dois teores de silagem de milho e da suplementação com soja extrusada sobre o perfil de ácidos graxos na gordura do leite. Oito vacas da raça Holandesa foram distribuídas em um quadrado latino duplo 4 x 4, em arranjo fatorial. Os tratamentos foram: alta silagem de milho e baixo lipídio, alta silagem de milho e alto lipídio, baixa silagem de milho e baixo lipídio e baixa silagem de milho e alto lipídio. Os períodos experimentais tiveram duração de 21 dias cada. As amostras de leite foram coletadas nos dias 18 e 19 de cada período experimental. O aumento dos teores de lipídios nos dois níveis de silagem diminuiu as concentrações de ácidos graxos de cadeia curta (C4:0 - C12:0). O teor de ácido linoleico conjugado (cis-9 trans-11 C18:2) aumentou de 3,72 para 4,85, e de 4,60 para 5,89mg/g, quando a soja extrusada foi utilizada em dietas com alto e baixo nível de silagem de milho, respectivamente. O aumento no teor de lipídios na dieta resultou em maior concentração de trans-11 C18:1. O ácido graxo trans-10 C18:1 tendeu a aumentar com a elevação do teor de lipídios na dieta. Houve correlação significativa entre trans-10, cis-12 C18:2 e percentual de gordura do leite. A suplementação com soja extrusada diminuiu os ácidos graxos de cadeia curta e o ácido palmítico no leite. Além disso, esta oleaginosa aumentou a concentração de ácido linoleico conjugado (C18:2 cis-9 trans-11) e vacênico, com o aumento da qualidade do leite para o consumo humano.

The objective of this study was to evaluate the effects of two levels of maize silage and extruded soybeans supplementation on fatty acid profile in milk fat of dairy cows. Eight Holstein cows were distributed in a double 4x4 Latin Square design with a factorial arrangement. The treatment groups were: high maize silage and low lipid, high maize silage and high lipid, low maize silage and low lipid and low maize silage and high lipid. The experimental periods lasted 21 days. Milk samples were collected on days 18 and 19 of each experimental period. The increase of lipid contents in high and low maize silage diets decreased short chain fatty acids concentrations (C4:0 - C12:0). The conjugated linoleic acid content (cis-9 trans-11 C18:2) increased from 3.72 to 4.85, and 4.6 to 5.89mg/g, when extruded soybeans was used in high and low level of corn silage, respectively. The increase in dietary lipids content resulted in higher trans-11 C18:1 fatty acid concentration. Fatty acid trans-10 C18:1 tended to increase with the elevation of the lipids content in the diet. There was significant correlation between trans-10, cis-12 C18:2 and milk fat percentage. The extruded soybeans supplementation decreased shortchain fatty acids and palmitic acid in milk. In addition, this oilseed enhanced the concentration of conjugated linoleic acid (C18:2 cis-9 trans-11) and vaccenic acid, which improved the milk quality for the human health.