377 Evaluation of Feed Intake, Feed Efficiency and Days on Trial in Growing Goats Fed a Total Mixed Diets Using Growsafe Feeding Technology

Abstract The objectives of this study were to evaluate the effects of breed and days on trial (DOT) on feed intake, growth rate, and feed efficiency of growing goats. Nineteen female goats (10 Alpine and 9 Spanish) with an initial BW of 38.8 ± 2.8 and 35.5 ±3.1 kg, respectively, were randomly assigned within breed to one of two pens (5 goats/pen), each equipped with GrowSafe feed bunks. A pelletized total mixed diet (TMD) was fed twice per day and goats had ad libitum access to feed and water throughout the 84-d trial. Daily feed intake (DMI) was collected with GrowSafe automated feeding system, and BW was measured biweekly. Linear regression of 14-d BW on DOT was used to derive ADG, mid-test metabolic BW (MBW) and expected DMI of individual goats at 42, 56, 70, and 84 DOT. Expected DMI was predicted by linear regression of DMI on MBW and ADG, with RFI calculated as a difference between actual and expected DMI for each DOT. Data were analyzed using a repeated-measures model with a fixed effect of breed, DOT as a repeated measure, and breed x DOT interaction with a pen as a random effect. The interaction was not significant for either of the response variables. Alpine goats had greater (P < 0.05) initial and final BW (37.6 kg and 51.7 kg, respectively) than Spanish goats (34.7 kg and 46.5 kg, respectively) although ADG (0.233 kg/d vs 0.191 kg/d) did not differ. DMI (P = 0.10) and RFI (P = 0.09) tended to be greater in Alpine than in Spanish goats (0.57 kg vs -0.64 kg). However, G:F was not affected (P > 0.70) by breed. As DOT increased from 42 to 84, MBW increased, while ADG, DMI, and G:F decreased. Further research is warranted to determine changes in phenotypic variances of ADG and DMI to determine the minimal DOT needed to accurately measure feed efficiency in growing goats. Our results suggest that Spanish goats tended to consume less feed and tended to be more efficient (negative RFI) than their counterpart Alpine goats. Further research is needed to compare the life-cycle efficiency of Alpine and Spanish goats.