V. Sáinz de la Maza-Escolà*1, G. Giovagnoni1, G. Petroni1, R. Paratte1, G. Bonacini2, A. Piva1,3, and E. Grilli3,4
1Vetagro S.p.A, Reggio Emilia, Italy,
2University of Bologna, DIMEVET, Ozzano dell’Emilia, Bologna, Italy,
3Vetagro Inc., Chicago, IL.
4Carra Mangimi, Bogolese di Sorbolo, Italy
Lysine (Lys) has been identified as a limiting amino acid (AA) for milk and milk protein production in lactating dairy cows. A 30-d pen study was conducted in a commercial Parmigiano-Reggiano to evaluate the effect of supplementing a rumen-protected lysine product (Relys®50; Vetagro S.p.A.; Reggio Emilia, Italy) on lactation performance in high-yielding dairy cows. One hundred ninety-five multiparous Holstein cows (3 ± 1.1 lactations [mean ± SD], and 150 ± 85 days in milk [DIM]) were randomly assigned to one of two groups: Control (n = 95; CON; basal diet) and RPL (n = 100; CON + 45 g/d of Relys®50 [50% HCl-Lysine]). Basal diet was supplemented with rumen-protected methionine (30 g/d of Timet®; 55% DL-methionine [Met]; Vetagro S.p.A) to provide 1.14 g of Met/Mcal metabolizable energy (ME). Respectively, CON and RPL diets were formulated at 2.86 and 3.04 g of Lys/Mcal ME, and 2.5:1 and 2.7:1 Lys:Met ratio. Cows were housed in free-stall pens and milked twice a day. Milk yield was recorded daily, and milk components were analyzed once a week. Data was divided by stage of lactation according to DIM (early [0-35], peak [36-90], mid [91-150], and late [151-305] and analyzed under a mixed model with the random effect of cow and the fixed effects of lactation, date and days in milk, treatment and their interaction. Supplementation of RPL increased milk yield in mid (P=0.12) and late (P=0.03) lactation compared to CON. In early lactation cows, milk protein and casein tended to increase in RPL compared to control cows (P<0.15). Overall, milk casein yield increased 40 g in RPL cows compared to CON (P<0.15). Milk urea nitrogen was significantly reduced in peak and mid lactating cows fed RPL relative to CON (P<0.05). Differential somatic cell count was lower in RPL cows across all lactation compared to CON (P<0.15). We conclude that feeding Relys®50 is a valid strategy for AA balancing and positively affects milk performance and nitrogen utilization in lactating dairy cows.
Discover more: Florence_EAAP_Book_Abstracts