RESUMEN
Sixty Alpine does (initial BW 47+/-1.3kg) were used to determine effects of dietary inclusion of different levels of partially hydrogenated tallow on performance in early lactation (weeks 3-11). Treatments entailed a 30% concentrate, negative control (NC) diet and five diets higher in concentrate (42-46%) with 0, 1.5, 3.0, 4.5 or 6.0% DM of partially hydrogenated tallow (0T, 1.5T, 3.0T, 4.5T and 6.0T, respectively). DM intake was 1.54kg per day for the NC and 1.86, 1.80, 1.99, 2.17 and 1.96kg per day for the five tallow treatments, respectively, BW was similar among treatments and increased as the trial progressed (47.4, 48.4, 49.8, 50.4, 50.8 and 51.3kg at weeks 3, 5, 7, 9, 11 and 13, respectively). Milk yield was lower (P<0.05) for NC (2.61kg per day) compared with the mean of the other diets and changed quadratically (P<0.05) as tallow level increased (2.85, 3.08, 3.14, 3.21 and 2.69kg per day for the five tallow treatments, respectively). Milk fat concentration was lower (P<0.05) for NC (2.94%) than for the mean of other diets and increased linearly (P<0.05) with increasing tallow level (3.00, 3.17, 3.34, 3.48 and 3.58%) whereas, milk protein concentration was not affected by level of tallow (2.72, 2.80, 2.93, 2.85, 2.90 and 2.90% for NC, and the five tallow treatments, respectively). The estimated NE(l):4% fat-corrected milk yield ratio was 0.93Mcal/kg for NC and 1.30, 1.11, 1.21, 1.37 and 1.44Mcal/kg for the five tallow treatments, respectively. The results indicated that in Alpine does, milk yield in early lactation increased as dietary tallow level was increased to 3 and 4.5% but decreased when the level was increased to 6%, although milk fat concentration increased linearly and the protein level was unchanged. These results suggest beneficial usage by lactating Alpine does of low to moderate levels of partially hydrogenated tallow in diets moderate in concentrate level, although ingredient availability and costs will influence ultimate dietary ingredient decisions.
