Publicação: Dietary chitosan improves nitrogen use and feed conversion in diets for mid-lactation dairy cows
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Feed additives and fat sources have been used to meet high productive dairy cow energy requirements. This study aimed to evaluate dietary chitosan and soybean oil effects on mid-lactation dairy cow intake, digestibility, metabolism and productive performance. Twenty-four Holstein cows (134.7±53.1 days in milk, 36.14±5.32 kg/day of milk yield, and 581.2±73.6 kg of body weight, Mean±SD) were used in a replicated 4×4 Latin square design with 21-d periods, with 14 d of adaptation and 7 d for data collection. The treatment arrangement was a 2×2 factorial design with two levels of chitosan (0 and 4 g/kg of dietary dry matter – DM) and two levels of soybean oil (0 and 33 g/kg of dietary DM). Chitosan decreased intake only in diets without oil (P<0.05). Regardless of fat addition, chitosan increased DM and CP digestibility (P<0.05). Soybean oil and chitosan increased total serum cholesterol (P<0.05). Chitosan diet had higher urea plasma concentration than control diet (CON) (P<0.05). Over all, soybean oil increased propionate and decreased acetate ruminal molar proportion, and therefore decreased acetate:propionate ratio (P<0.05). Chitosan decreased milk yield, nitrogen use and feed conversion efficiencies in oil-diets (P<0.05). Soybean oil decreased short and medium milk fatty acids concentration (P<0.05). Chitosan had no effect on long-chain milk fatty acids in diets with soybean oil (P>0.05). However, in free oil-diets, chitosan increased milk polyunsaturated fatty acids concentration, nitrogen and energy efficiency. Chitosan addition in free-fat diets improved feed efficiency, increased milk unsaturated fatty acids concentration and association with soybean oil negatively affect animal performance.
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Chitin, Digestibility, Fatty acids, Milk yield, Ruminal fermentation
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Inglês
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Livestock Science, v. 201, p. 22-29.
