A study was conducted on 19 Holstein dairy farms in the Parmigiano-Reggiano production area with the aim to evaluate on a herd base the milk nitrogen use efficiency (MNE) and casein nitrogen use efficiency (CNE) of dairy cows fed hay-based total mixed ration (TMR). Dry matter intake was calculated based on the amount of diet offered and refused during 2 days. The diets were analysed to estimate nitrogen (N) content and calculate N intake. Data on total milk yield (MY) and milk composition -including casein concentration- were recorded on a farm basis and; milk N yield (N milk), milk casein nitrogen yield (CNY) were determined to calculate MNE and CNE as N milk/N intake and CNY/N intake, respectively. The farms were then categorised based on the daily average MY/cow as low -L- (MY/cow ≤33 kg/day, 9 farms) and high -H- (MY/cow >33 kg/day, 10 farms). MNE and CNE data were normally distributed and analysed as a function of farm categories through the mixed model, with farm as random effect. MNE and CNE ranged from 0.24 to 0.37 and from 0.19 to 0.29, respectively. The L farms (average size: 213±94 cows; 181±20 DIM; average diet: 15.1% CP, 38.7% NDF and 21.5% starch (DM basis)) had an average MY of 30.86±1.60 kg/cow/day. The H farms (average size: 176±95 cows; 174±20 DIM; average diet: 15.3% CP, 37.9% NDF; 22.0% starch diets (DM basis)) had an average MY of 35.86±2.59 kg/cow/day. The H farms showed a trend for higher MNE (0.30 vs 0.27; P=0.068) and CNE (0.23 vs 0.21; P=0.075) in comparison to L farms. Overall, given similar levels of dietary CP, these results seem to confirm the higher MNE of high yielding herds. The CNE could be a further parameter to evaluate the efficiency of N use when milk is processed for cheese production. This project has received funding from the European Union’s Horizon 2020 research and innovation programme under the Marie Skłodowska-Curie grant agreement No 777974. We thank the farmers and the volunteer students involved in the study.
Milk and casein nitrogen use efficiency of dairy farms in the Parmigiano Reggiano production area / Simoni, Marica; Pitino, Rosario; ANOUAR Belaid, M.; Foskolos, Andreas; Summer, Andrea; Quarantelli, Afro; Righi, Federico. - 26:(2020), pp. 139-139. (Intervento presentato al convegno 71st Annual Meeting of the European Federation of Animal Science tenutosi a Virtual meeting nel 1-4 December 2020) [10.3920/978-90-8686-900-8].
Milk and casein nitrogen use efficiency of dairy farms in the Parmigiano Reggiano production area
MARICA SIMONI
;ROSARIO PITINO;ANDREA Summer;AFRO Quarantelli;FEDERICO Righi
2020-01-01
Abstract
A study was conducted on 19 Holstein dairy farms in the Parmigiano-Reggiano production area with the aim to evaluate on a herd base the milk nitrogen use efficiency (MNE) and casein nitrogen use efficiency (CNE) of dairy cows fed hay-based total mixed ration (TMR). Dry matter intake was calculated based on the amount of diet offered and refused during 2 days. The diets were analysed to estimate nitrogen (N) content and calculate N intake. Data on total milk yield (MY) and milk composition -including casein concentration- were recorded on a farm basis and; milk N yield (N milk), milk casein nitrogen yield (CNY) were determined to calculate MNE and CNE as N milk/N intake and CNY/N intake, respectively. The farms were then categorised based on the daily average MY/cow as low -L- (MY/cow ≤33 kg/day, 9 farms) and high -H- (MY/cow >33 kg/day, 10 farms). MNE and CNE data were normally distributed and analysed as a function of farm categories through the mixed model, with farm as random effect. MNE and CNE ranged from 0.24 to 0.37 and from 0.19 to 0.29, respectively. The L farms (average size: 213±94 cows; 181±20 DIM; average diet: 15.1% CP, 38.7% NDF and 21.5% starch (DM basis)) had an average MY of 30.86±1.60 kg/cow/day. The H farms (average size: 176±95 cows; 174±20 DIM; average diet: 15.3% CP, 37.9% NDF; 22.0% starch diets (DM basis)) had an average MY of 35.86±2.59 kg/cow/day. The H farms showed a trend for higher MNE (0.30 vs 0.27; P=0.068) and CNE (0.23 vs 0.21; P=0.075) in comparison to L farms. Overall, given similar levels of dietary CP, these results seem to confirm the higher MNE of high yielding herds. The CNE could be a further parameter to evaluate the efficiency of N use when milk is processed for cheese production. This project has received funding from the European Union’s Horizon 2020 research and innovation programme under the Marie Skłodowska-Curie grant agreement No 777974. We thank the farmers and the volunteer students involved in the study.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
