A study was performed to validate the Cornell Net Carbohydrate and Protein System for dairy cows in late lactation and to verify the effect of three nitrogen sources on milk yield. Nine non-pregnant Holstein cows in late lactation (65315 kg BW on average) were used in a 33 Latin square design during three 18-day trials. Three isoproteic (18.09 CP%DM on average) and isoenergetic (1.51 Mcal NE/kg DM on average) Total Mixed Rations were compared. The dry matter of the mixed diets consisted of lucerne hay (33%), maize silage (34%), one of three by-products (soybean meal 3.13% for diet S; sunflower meal 3.88 for diet SF; corn gluten meal 1.88% for diet CG), and the same farm concentrate for the remaining parts. DMI, BWG and milk yield and composition were not affected by the different protein sources. The relationship between the predicted CNCPS and the observed data shows that the Cornell predictive equations are inaccurate. DMI, milk yield and BWG were overestimated. The best statistical result was obtained for milk yield as a function of MP in the diets (R2=0.53).
Evaluation of the Cornell net carbohydrate and protein system for dairy cows in late lactation
DE VINCENZI, Sergio;COSTANTINI, Francesco;
2001
Abstract
A study was performed to validate the Cornell Net Carbohydrate and Protein System for dairy cows in late lactation and to verify the effect of three nitrogen sources on milk yield. Nine non-pregnant Holstein cows in late lactation (65315 kg BW on average) were used in a 33 Latin square design during three 18-day trials. Three isoproteic (18.09 CP%DM on average) and isoenergetic (1.51 Mcal NE/kg DM on average) Total Mixed Rations were compared. The dry matter of the mixed diets consisted of lucerne hay (33%), maize silage (34%), one of three by-products (soybean meal 3.13% for diet S; sunflower meal 3.88 for diet SF; corn gluten meal 1.88% for diet CG), and the same farm concentrate for the remaining parts. DMI, BWG and milk yield and composition were not affected by the different protein sources. The relationship between the predicted CNCPS and the observed data shows that the Cornell predictive equations are inaccurate. DMI, milk yield and BWG were overestimated. The best statistical result was obtained for milk yield as a function of MP in the diets (R2=0.53).I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
