RESUMEN
Abstract Background: Demand for naturally enriched foods is increasing worldwide. Animal nutrition allows incorporating nutraceutical molecules into milk. These molecules are intended for improving human health. Objective: To evaluate the effects of pelleting and monensin addition to the diet on intake, digestibility of dry matter (DM) and nutrients, milk yield and composition, and fatty acids (FA) profile in cows kept on pasture and supplemented with concentrate containing ground flaxseed (GF). Methods: Four Holstein cows were assigned to the following treatments: 1) concentrate with GF; 2) GF + 32.93 mg/Kg monensin (GFM); 3) GF pelleted (GFP); 4) GF pelleted + 32.93 mg/Kg monensin (FMP). Results: Treatments did not show effects on digestibility of dry matter (DM) and nutrients or feed intake, with the exception of ether extract intake, which was reduced by 28% with pelleting. Addition of monensin increased the conjugated linoleic acid (CLA) concentration by 47%. Pelleting increased the concentrations of CLA (70%), polyunsaturated FA (PUFA; 25%), and monounsaturated FA (MUFA; 16%), and reduced the concentrations of steric acid (C18) in 19% and total saturated FA (SFA; 14%). Conclusion: Pelleting and monensin does not alter feed intake and digestibility of DM and nutrients. Pelleting of concentrate feed containing flaxseed improves milk FA quality.
Resumen Antecedentes: La demanda por alimentos naturalmente enriquecidos se ha venido incrementado en todo el mundo. A través de la nutrición animal es posible incorporar moléculas nutracéuticas en la leche. El uso de estas moléculas pretende mejorar la salud humana. Objetivo: Evaluar los efectos de la peletización y la monensina sobre la ingesta, digestibilidad de la materia seca (DM) y nutrientes, producción de leche, composición y perfil de ácidos grasos (FA) en leche de vacas en pastoreo que consumen alimento concentrado formulado con linaza molida (GF). Métodos: Cuatro vacas Holstein fueron distribuidas en los siguientes tratamientos: 1) ración conteniendo GF; 2) GF + 32,93 mg/Kg de monensina (GFM); 3) GF en pellets (GFP); 4) GF en pellets + 32,93 mg/Kg de monensina (FMP). Resultados: Los tratamientos no mostraron efectos en el consumo y digestibilidad de la DM y nutrientes, excepto por el consumo de extracto etéreo, con una reducción del 28% en las raciones peletizadas. La monensina incrementó la concentración de ácido linoleico conjugado (CLA) en 47%. La peletización aumentó el contenido de CLA (70%), FA poliinsaturados (PUFA; 25%) y FA monoinsaturados (16%); y redujo las concentraciones de C18 en 19%, y FA saturados total en 14%. Conclusión: El peletizado y la monensina no alteran la ingesta de alimento ni la digestibilidad de la DM y nutrientes. El proceso de peletizado aplicado a concentrados que contienen linaza mejora la calidad de los ácidos grasos de la leche.
Resumo Antecedentes: A procura por alimentos naturalmente enriquecidos tem aumentado por parte dos consumidores. Através da nutrição animal é possível incorporar ao leite moléculas nutracêuticas, essas moléculas são conhecidas por melhorarem a saúde humana. Objetivo: Avaliar os efeitos da peletização e monensina sobre o consumo, digestibilidade da matéria seca (DM) e nutrientes, produção de leite, composição e perfil de ácidos graxos (FA) no leite de vacas em pastejo e suplementadas com concentrado contendo linhaça moída (GF). Métodos: Quatro vacas Holandesas foram distribuídas nos tratamentos: 1) concentrado contendo GF; 2) GF + 32,93 mg/Kg de monensina (GFM); 3) GF peletizado (GFP); 4) GF peletizado + 32,93 mg/Kg de monensina (FMP). Resultados: Os tratamentos não apresentaram efeitos sobre consumo e digestibilidade da DM e dos nutrientes, exceto para o consumo de extrato etéreo, com redução de 28% com a peletização do concentrado. A adição de monensina aumentou a concentração de ácido linoleico conjugado (CLA) em 47%. A peletização aumentou os teores de CLA (70%), FA poli-insaturados (25%) e FA monoinsaturados (16%); e reduziu as concentrações de C18 em 19% e AG saturados totais em 14%. Conclusão: Peletização e monensina não alteram o consumo e digestibilidade da DM e dos nutrientes. O processo de peletização aplicado em concentrados contendo linhaça melhora a qualidade dos FA do leite.
RESUMEN
Pasture-based dairy production has been a major source of income for most family farms in the south of Brazil. Increasing milk prices have spurred an increase in grain supplementation, which has been poorly implemented, resulting in low levels of efficiency. To evaluate the consequences of supplementation on milk production and composition, grazing behavior and economic return, the widely used grain management system (CC-commercial concentrate, containing 21% CP, offered at 1 kg per 3.7 L of milk) was compared with an energy supplement (GC-ground corn, with 9.5% CP, offered at 0.4% of live weight). Ten Holstein cows were paired into two groups, and subjected to the two treatments in a crossover design. The cows remained in the same grazing group, and the grain supplement was offered individually at milking time and consumed completely. Each experimental period lasted 14 days, with 10 days for diet adaptation and four days for data collection; individual milk production and samples were collected to determine levels of fat, protein, lactose, carotenoids, vitamin A and N-urea. Grazing behavior was observed (scans every 5 min) in the first 4 h after the morning milking, and chemical composition of hand plucked samples of forage were measured. The cost of the supplement and profitability per treatment were calculated. Cows supplemented with GC consumed herbage with higher crude protein (CP: 16.23 vs. 14.62%; p < 0.05), had higher biting rate (44.21 vs. 39.54 bites/min; p < 0.03) and grazing time (22.20 vs. 20.55 scans; p < 0.05) than when receiving CC. There were no differences in milk composition between treatments (p > 0.05). However, higher concentrations of ß-carotene and total carotenoids were detected in the milk of cows at 70-164 days of lactation, compared to <70 days of lactation (p < 0.05). Milk production was higher (13.19 vs. 11.59 kg/day; p < 0.05) when cows consumed CC, but resulted in lower profitability compared to GC (US$ 4.39 vs. US$ 4.83/cow per day). Our results show that higher productivity does not necessarily improve profitability. Cows receiving supplement with lower levels of protein were able to adjust their grazing behavior to meet their protein needs and this level of diet modification did not alter milk composition.