Produção leiteira, composição do leite e perfil bioquímico sanguíneo de vacas lactantes sob suplementação com sal aniônico

Abstract

RESUMO -Objetivou-se avaliar os efeitos da inclusão de sal aniônico na dieta sobre as características físicas e a composição química do leite, o perfil bioquímico sanguíneo, a produção de leite, o peso e a condição corporal de vacas em lactação. Foram utilizadas 20 vacas da raça Jersey distribuídas em duas dietas, uma sem adição de sal aniônico e outra com adição de 0,25 kg/dia de cloreto de amônio. O delineamento empregado foi o completamente casualizado. As vacas sob suplementação com sal aniônico apresentaram menor pH urinário e aumento das concentrações sanguíneas de ureia, cálcio e magnésio. Com a dieta aniônica, o leite precipitou com menores concentrações de etanol, apresentou menor densidade, porcentagens de lactose, proteína e imunoglobulina, porém maior teor de cálcio iônico. O fornecimento de dieta aniônica durante a lactação resultou em acidose metabólica, o que alterou o perfil bioquímico sanguíneo e as características físico-químicas do leite.Palavras-chave: acidose metabólica, dieta aniônica Milk yield, milk composition and biochemical blood profile of lactating cows supplemented with anionic saltABSTRACT -The objective of this work was to evaluate the inclusion of anionic salt in the diet on the physical characteristics and chemical composition of milk, biochemical blood profile, milk yield, body weight and condition. It was used 20 Jersey cows, distributed into two diets, a diet with no addition of anionic salt and one diet with addition of 0.25 kg/day of ammonium chloride. It was used a completely randomized design. Cows supplemented with anionic salt presented lower urinary pH and increase of blood contents of urea, calcium and magnesium. With the anionic diet, milk precipitated with lower ethanol concentration and it presented lower density, percentages of lactose, protein and immunoglobulin, but higher ionic calcium content. Supply of anionic diet during lactation resulted in metabolic acidosis, which altered the blood biochemical profile and milk physical-chemical characteristics.

Effect of dietary cation-anion difference on performance of lactating dairy cows and stability of milk proteins

“…Moreover, most studies reported that the nutritional and metabolic conditions of dairy cows were the main factors that changed the milk stability (Zanela et al, 2006;Marques et al, 2011;Barbosa et al, 2012). Barbosa et al (2012) reported that cows fed with nutrientdeficient diets produced milk with lower concentrations of κ-CN and, consequently, lower ethanol stability when compared with milk from cows fed balanced diets.…”

“…Barbosa et al (2012) reported that cows fed with nutrientdeficient diets produced milk with lower concentrations of κ-CN and, consequently, lower ethanol stability when compared with milk from cows fed balanced diets. Alternatively, Marques et al (2011) reported that the metabolic acidosis of dairy cows, through the action of parathyroid and 1,25-dihydroxycholecalciferol hormones, may increase milk concentrations of iCa and reduce the MES. Besides the iCa and κ-CN concentrations, other dairy components were also associated with lower milk stability, such as the formation of β-LG protein complexes with κ-CN in the micelle, MUN, temperature, pH, and concentrations of citrate and phosphate in milk (Jeurnink and De Kruif, 1995;Singh, 2004;Lewis, 2011).…”

Subclinical intramammary infection does not affect bovine milk ethanol stability

“…Stumpf et al (2013) reported that feed restriction may increase the permeability of mammary gland cell tight junctions and reduce MES due to saline imbalance. Martins et al (2015) and Marques et al (2011) observed that blood acidification increases milk concentration of iCa and reduces MES, suggesting that ruminal and metabolic acidosis, heat stress, and reduction in dietary cation-anion differences may reduce MES. Thus, the occurrence of unstable nonacid milk in Brazil and other countries that routinely use ethanol test for milk evaluation can be closely associated with nutrient imbalance, digestive disturbances, as well as genetic and environmental conditions, but not with subclinical IMI.…”

“…Results were expressed by the lowest concentration of ethanol in which milk coagulation occurred (MARQUES et al, 2011).…”

“…The increase of milk concentrations of iCa may reduce the negative charges of the casein micelles and the strength of electrostatic repulsion between them, which reduces the casein resistance to coagulation during contact with ethanol or milk heat processing (BARROS et al, 1999). Previous studies reported that feed restriction (BARBOSA et al, 2012;STUMPF et al, 2013) and metabolic disorders associated with blood acid-base changes (MARQUES et al, 2011;FAGNANI et al, 2014;MARTINS et al, 2015) of dairy cows could be followed by increased milk concentration of iCa and reduced stability of milk proteins. Other milk characteristics were also associated with a lower stability, such as changes in concentrations of caseins' subunits and β-lactoglobulin, milk urea nitrogen (MUN), temperature of the milk sample during analysis, pH, and concentrations of citrate and phosphate (JEURNINK; KRUIF, 1995;SINGH, 2004;LEWIS, 2011).…”