IMPROVING NUTRIENT DIGESTIBILITY TO ENHANCE FORAGE UTILIZATION IN LACTATING DAIRY COW FEEDING SYSTEMS
Location: Dairy Forage and Aquaculture Research
Title: The Effect of Dietary Alfalfa Silage to Corn Silage Ratios on Cow Performance and Ammonia Nitrogen Emission
Submitted to: Joint Meeting of the ADSA, AMSA, ASAS and PSA
Publication Type: Abstract Only
Publication Acceptance Date: March 15, 2010
Publication Date: June 15, 2010
Citation: Arndt, C., Wattiaux, M.A., Powell, J.M. 2010. The Effect of Dietary Alfalfa Silage to Corn Silage Ratios on Cow Performance and Ammonia Nitrogen Emission. Joint Meeting of the ADSA, AMSA, ASAS and PSA. Abstract W327. 692 J. Anim. Sci. Vol. 88, E-Suppl. 2/J. Dairy Sci. Vol. 93, E-Suppl. 1/Poult. Sci. Vol. 89, E-Suppl.
The objective was to determine the effect of varying alfalfa silage (AS) to corn silage (CS) ratio in a 55:45 forage:concentrate ratio (% DM) total mixed ration on performance of lactating cows and ammonia N emission. Sixteen multiparous Holstein cows were blocked by DIM and randomly assigned to balanced 4 x 4 Latin squares. Cows were housed in modified tie-stall barns with 4 chambers designed to house 4 cows per chamber. Air samples were collected for about 17 h/d, on 3 consecutive days of each period and analyzed for ammonia N with a Photo-acoustic Multi-gas Monitor (Innova Model 1412). Dietary treatments were 20:80 (AS20), 40:60 (AS40), 60:40 (AS60), and 80:20 (AS80). As AS increased, expeller soybean meal substituted for soybean meal to maintain RUP above 6%. Dietary CP content of the diets increased with an increased proportion of AS in the diet and averaged 16.8, 17.2, 17.5, and 18.2% of diet DM for AS20, AS40, AS60, and AS80, respectively. No difference was observed for DMI (26.7 kg/d), milk yield (40.8 kg/d), milk efficiency (milk yield/DMI; 1.53), fat content (3.85%), protein yield (1.20 kg/d) and MUN (16.2 mg/dL). A linear and quadratic response was observed for fat yield which averaged 1.51, 1.59, 1.60 and 1.57 kg/d for AS20, AS40, AS60 and AS80, respectively, with the AS20 diet being lower than the other diets (P<<0.05). True milk protein content decreased (P<0.05) from 3.01% in AS20 to 2.96% in AS40 and AS60, and was further reduced to 2.88% in AS80 compared to other treatments. Nitrogen intake increased linearly (701 to 791 g/d) with increasing proportion of AS in the diet whereas milk N decreased linearly (190 to 183g/d). No difference was observed in ammonia emission rate among treatments (averaging 0.70 +/- 0.16g N/cow/h). Similarly, there was no difference in ammonia-N emission per unit of N intake (0.023 +/-0.006g ammonia N/g N intake) or per unit of milk N (0.089 +/-0.020g ammonia N/g milk N). Despite higher N intakes with increasing proportion of AS in the diet, no difference in ammonia emission was observed from cows fed and managed in a tie stall barn.