MEAT GOAT SIRE EVALUATION TEST USING THE GROWSAFE 4000 SYSTEM David Seymour WVU Extension Agent – Pendleton County Dave.Seymour@mail.wvu.edu 304-358-2286
Objective • Determine the feasibility of adapting the GroSafe system to meat goat bucks for collecting data for a sire performance test.
GrowSafe System GrowSafe Systems collect individual feed data to measure feed efficiency in terms of net feed intake.
Adapting to Goats: Was a challenge
2006 Buck Feeding Trial • 23 commercial bucks from one commercial herd were evaluated on the GrowSafe system for 41 days. • ADG ranged from 0.46 to 1.12 lbs/day with the group averaging 0.67 lbs/day. • Ultrasound carcass data from the rams on the trial, adjusted to 80.43 pounds, ranged from 0.04-0.12 inches for backfat and 1.27-1.93 square inches for LEA.
What makes this performance test unique? • Feed Efficiency Data / Residual Feed Intake (RFI)
Understanding RFI and its Implications Residual Feed Intake
Relationship of ADG w/ Maturity ADG → Must grow to larger size to equal stage of finish. i.e. greater mature size Physiological maturity →
Genetic Scaling Theory • Increased growth rate leads to increased mature weight and a consequent increase in maintenance requirements. • In most ruminant production systems 65-75% of the total lifetime dietary energy is used for maintenance • Only 5-22% is used for protein deposition. • Maintenance energy requirements have been shown to be moderate to highly heritable (h2=0.22-0.71)
If so important then why have we waited until now? • Difficulty in obtaining necessary measurement: • Gain • Individual feed intakes • ??? validity of data under non-production environment. • Understand what the data means and what concerns there are with the data generated.
Efficiency of Conversion of Feed • RFI (actual – expected) • Considerable individual animal variation in feed intake above and below what is expected based on size and growth
RFI –The Practice • Increase in weight over time is measured with multiple observations and modeled by regression. • Normalization of the growth curve to avoid periods of morbidity or restriction. • Initial weight, ADG, midpoint weight and final weight are calculated from the regression. • Intake is regressed on mid BW+ ADG • Mid BW is very important! • This gives us an expected value for animals of similar weights and rates of gain.
RFI – The Theory • RFI is independent of growth and maturity patterns. • RFI is a more sensitive and precise measure of feed quality based on energy intake and requirements. • Uses accurate contemporaries for comparison • Positive RFI indicates less efficient use of energy compared to contemporaries • Negative RFI indicates greater efficiency • RFI has been shown to have a heritability coefficient near .45, similar to growth.
Results • Residual Feed Intake (RFI), ranged from 3.24 to (-)2.54 lbs/day. The buck with the RFI value of (-) 2.54 was more efficient and consumed 2.54 pounds less feed than was expected per day. • Difference between the most and least efficient bucks was 5.78 lbs of feed per day (a cost of $ .65 per day
Result • The trial demonstrated the GroSafe feeding system with modifications can be used to test meat goats.