Evaluating of feed aditives for dairy cows

The objective of this study was to evaluate the effects of different additives in dairy cows feeding on nutrient intake, total apparent digestibility of dry matter and nutrients, ruminal fermentation, milk yield and composition, concentrations of blood parameters and energy and nitrogen balances; 24 Holstein cows 31.44 ± 4.83 kg/day of milk yield, 586.07 ± 79.63 kg of BW and 175.89 ± 99.74 days in milk; mean ± SD), 16 intact and 8 ruminally fistulated. The animals were randomly assigned in six 4 x 4 Latin-square (contemporaneous and balanced) design to receive one of following diets: 1) Control (CO), diet without inclusion of monensin, chitosan or essential oils; 2) Crina® (CRI), inclusion of the mixture of essential oils (Crina&reg; Ruminants - SM Nutritional products TORTUGA) at 1g/cow/day; 3) Chitosan (QUI), inclusion of 150 mg/kg BW of chitosan, and; 4) Monensin (MON), inclusion of 24 mg/kg of diet DM of sodic monensin (DSM Monesin, TORTUGA). No differences in DMI and nutriente intakes were observed (P<0.05) for cows fed different treatments. Total apparent digestibility of DM and organic matter were higher for cows fed Q when compared to cows fed CR. The crude protein digestibility was decreased when cows were fed CR when compared to cows fed the diets containing other additives (M and Q). There were no differences (P<0.05) in milk yield and composition among cows fed experimental treatments. The intakes of digestible and metabolizable energy were higher for cows fed Q than cows fed C and M. The efficiency of energy utilization was higher for cows fed C when compared to cows fed Q. Monensin increased serum total cholesterol compared to C. The excretion of fecal nitrogen (g /day) was lower for the animals supplemented with CR compared to other additives to fecal nitrogen excretion (% of total nitrogen) differed just for animals fed Q. Cows fed Q had higher nitrogen balance than cows fed M. Experimental treatments did not alter pH, concentration of ruminal acetate (mmol / L) was decreased when cows were fed with M and Q, compared to C. Higher concentration of propionate (mmol / L) was observed for cows fed M than cows fed CR. Moreover, cows fed M had butyrate concentration (mmol / L) decreased compared to cows fed C, and short chain fatty acids concentration (mmol / L) was decreased when additives were added to diets. Total concentration of short chain fatty acids (mmol / L) was reduced when monensin and essential oils were added to the diet. Thus, we conclude that the essential oils (Crina Ruminants), responses were not positive for the variables evaluated, possibly caused by intense antimicrobial activity not only selective to the desired microorganisms, leading to adverse effects. However the use of chitosan in dairy cows have similar results of monensin use or above the control diet depending on the variables evaluated, and can be a great alternative nutrition of this animals (AU)