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Effectiveness of precision feeding in reducing N excretion in dairy cattle.

M. Terré



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Effectiveness of precision feeding in reducing N excretion in dairy cattle.
M. Terré*1,3, L. Morey2, D. Sabrià3, A. Bach4,1. 1Ruminant Department, IRTA Caldes de Montbui, Spain, 2GIRO, IRTA Caldes de Montbui, Spain, 3EVAM, IRTA Monells, Spain, 4ICREA Barcelona, Spain.

Eleven primiparous and 17 multiparous Holstein dairy cows (723 ± 3.1 kg of BW; 34.5 ± 1.69 kg/d of milk;159 ± 17.7 DIM) were blocked by parity and DIM, and randomly assigned to a conventional (CONV) feeding scheme based on a unique TMR or to a precision feeding scheme (PREC) for a 21-d period. The CONV group was offered a TMR (1.63 Mcal/kg DM, 16.5% CP), and PREC cows were fed a partial mixed ration (PMR; 1.59 Mcal/kg DM, 13.5% CP) and a concentrate feed supplement, which contained different proportions of soybean meal, corn, and wheat middlings according to animal estimated needs above the PMR consumption twice daily in the milking parlor. Daily needs were calculated using NRC equations (2001) with a rolling average of performance data (milk yield and quality, and BW) from 10 preceding days, and subtracting the nutrients consumed from the PMR computed also using a rolling average from 10 preceding days. Daily TMR and PMR intake, milk yield and quality were daily recorded, and a N balance using spot sampling during the last 3 d of the study was performed. Animals following both feeding systems had similar milk yield, milk fat and protein content, and total DMI. However, CP intake was greater (P < 0.05) in CONV than in PREC cows (4.26 vs 3.70 ± 0.170, respectively, kg/d), and improvements (P < 0.05) in feed efficiency (1.47 vs 1.39 ± 0.170, respectively) and efficiency of N utilization (0.32 vs 0.29 ± 0.005, respectively) were observed in PREC compared with CONV fed cows. Total daily N urine excretion (197 vs 142 ± 11.7, respectively, g/d) and milk urea concentration (130 vs 77 ± 14.5, respectively, mg/dL) were greater in CONV than in PREC fed cows. Feeding cows using a precision feeding system based on daily milk yield and composition can reduce environment N excretion without impairing performance.

Keywords: efficiency, environment, nutrition.