The objective of this study was to evaluate whether providing chitosan (CHI) to cows fed diets supplemented with whole raw soybeans (WRS) would affect the nutrient intake and digestibility, ruminal fermentation and bacterial populations, microbial protein synthesis, N utilization, blood metabolites, and milk yield and composition of dairy cows. Twenty-four multiparous Holstein cows (141 ± 37.1 d in milk, 38.8 ± 6.42 kg/d of milk yield; mean ± SD) were enrolled to a 4 × 4 Latin square design experiment with 23-d periods. Cows were blocked within Latin squares according to milk yield, days in milk, body weight, and rumen cannula (n = 8). A 2 × 2 factorial treatment arrangement was randomly assigned to cows within blocks. Treatments were composed of diets with 2 inclusion rates of WRS (0 or 14% diet dry matter) and 2 doses of CHI (0 or 4 g/kg of dry matter, Polymar Ciência e Nutrição, Fortaleza, Brazil). In general, CHI+WRS negatively affected nutrient intake and digestibility of cows, decreasing milk yield and solids production. The CHI increased ruminal pH and decreased acetate to propionate ratio, and WRS reduced NH-N concentration and acetate to propionate in the rumen. The CHI reduced the relative bacterial population of Butyrivibrio group, whereas WRS decreased the relative bacterial population of Butyrivibrio group, and Fibrobacter succinogenes, and increased the relative bacterial population of Streptococcus bovis. No interaction effects between CHI and WRS were observed on ruminal fermentation and bacterial populations. The CHI+WRS decreased N intake, microbial N synthesis, and N secreted in milk of cows. The WRS increased N excreted in feces and consequently decreased the N excreted in urine. The CHI had no effects on blood metabolites, but WRS decreased blood concentrations of glucose and increased blood cholesterol concentration. The CHI and WRS improved efficiency of milk yield of cows in terms of fat-corrected milk, energy-corrected milk, and net energy of lactation. The CHI increased milk concentration [g/100 g of fatty acids (FA)] of 18:1 trans-11, 18:2 cis-9,cis-12, 18:3 cis-9,cis-12,cis-15, 18:1 cis-9,trans-11, total monounsaturated FA, and total polyunsaturated FA. The WRS increased total monounsaturated FA, polyunsaturated FA, and 18:0 to unsaturated FA ratio in milk of cows. Evidence indicates that supplementing diets with unsaturated fat sources along with CHI negatively affects nutrient intake and digestibility of cows, resulting in less milk production. Diet supplementation with CHI or WRS can improve feed efficiency and increases unsaturated FA concentration in milk of dairy cows.

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Our objective was to evaluate the effects of providing increasing levels of chitosan on nutrient digestibility, ruminal fermentation, blood parameters, nitrogen utilisation, microbial protein synthesis, and milk yield and composition of lactating dairy cows. Eight rumen-fistulated Holstein cows [average days in lactation = 215 ± 60.9; and average bodyweight (BW) = 641 ± 41.1 kg] were assigned into a replicated 4 × 4 Latin square design, with 21-day evaluation periods. Cows were assigned to be provided with four levels of chitosan, placed into the rumen through the fistula, as follows: (1) Control: with no provision of chitosan; (2) 75 mg/kg BW; (3) 150 mg/kg BW; and (4) 225 mg/kg BW. Chitosan had no effect on dry matter intake (P > 0.73); however, chitosan increased (P = 0.05) crude protein digestibility. Propionate concentration was increased (P = 0.02), and butyrate, isobutyrate, isovalerate and acetate : propionate ratio were decreased (P ≤ 0.04) by chitosan. Chitosan had no effect (P > 0.25) on acetate, pH and NH3 ruminal concentration. Glucose, urea, and hepatic enzyme concentrations in the blood were similar (P > 0.30) among treatments. Nitrogen balance was not affected, but chitosan increased milk nitrogen (P = 0.02). Microbial protein synthesis was not affected by chitosan (P > 0.44). Chitosan increased (P = 0.02) milk yield, fat-corrected milk, protein and lactose production. Chitosan changes ruminal fermentation and improves milk yield of lactating dairy cows; therefore, we conclude that chitosan can be used as a rumen modulator instead of ionophores in diets for dairy cows.

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.

Exogenous fibrolytic enzymes (EFE) can increase ruminal digestion of neutral detergent fiber (NDF) and improve its fermentation for cattle. Twenty-four multiparous Holstein cows (33.72 ± 7.63 kg milk/d and 176 ± 82.27 days in milk-DIM, at the start of the experiment) were used in a replicated 4 × 4 Latin square experimental design. Increasing doses of a commercial product was used to evaluate the effect of xylanase activity (100 units per gram of product) on intake and total-tract digestion of nutrients, sorting index, chewing time, milk yield and composition, N use, and ruminal fermentation. Treatments consisted of 0, 8, 16 or 24 g/d per cow of EFE product mixed into the concentrate. Corn silage was used as forage source. The basal diet had a forage-to-concentrate ratio of 50:50 (dry matter basis). Even though EFE supplementation had a positive linear effect on dry matter and NDF intake, it had no impact on total-tract digestion of nutrients. Moreover, this enzyme promoted a linear increase of the intake of feed with larger particle size (>19 mm) and quadratically affected rumination and chewing activity (hours), reaching the highest values at intermediate doses (8 g/d and 16 g/d). Treatments had no effect on milk yield and composition; however, the N use efficiency was linearly decreased by EFE, reducing thus the ability to synthesize milk and quadratically decreasing N retention. No treatment effect was found on ruminal pH, whereas a negative quadratic effect on ruminal NH 3-N concentration was significant. Regarding ruminal parameters, this enzyme supplementation provided linear increased in acetate, propionate, butyrate, and total short-chain fatty acids synthesis. As result, EFE supplementation improved DM and NDF intake, increasing the time spent chewing and ruminating, leading to a greater total short-chain fatty acids production in rumen. Nonetheless, EFE did not improve milk yield and composition of mid-lactating dairy cows.