The effect of supplemental lysine and threonine on growth and development of yearling horses.

The research article investigates the influence of lisine and threonine supplementation on the growth and progress of young, yearling horses. The study conducted tests over two experimental periods, each lasting 112 days, on thirty-nine Thoroughbred and Quarter Horse yearlings.

Experiment Design

• The horses were individually fed varying dietary treatments involving a pelleted concentrate containing corn, oats, and soybean meal, served twice a day, along with Coastal Bermuda grass hay.
• Three different concentrates were tested: the basal, the basal supplemented with .2% lysine, and the basal supplemented with .2% lysine and .1% threonine.
• The study recorded data every 28 days, such as feed intake, weight, withers (the highest part of the back) height, girth, hip height, body length, and hoof growth.
• For an accurate estimate of bone mineral content, initial and final radiographs were taken.
• The thickness of the croup or rear part of the horse’s body was measured ultrasonically.
• In the first experiment, the final croup fat thickness measurement was taken and in the second one, the initial and final croup fat was measured.
• Every 28 days, blood samples were taken for determining serum urea N and protein counts.

Observations and Conclusions

• The daily feed intake averages were 8.8 +/- .14, 9.0 +/- .13, and 9.2 +/- .13 kg for the basal, basal plus lysine, and basal plus lysine and threonine treatments, respectively.
• The average daily gain (ADG) was .57 +/- .02, .64 +/- .02, and .67 +/- .02 kg/day respectively for said treatments; which indicates that the supplementation of lysine and threonine promotes increased growth.
• The girth gain of the yearlings was 9.7 +/- .49, 10.1 +/- .46, and 11.3 +/- .47 cm for the three treatments, in order, supporting the same conclusion.
• The gain-to-feed ratios for the first experiment were 70.5, 70.8, and 75.5 g/kg for treatments A, B, and C, respectively, with no significant difference. In experiment 2, however, these ratios were 61.7, 70.8, and 70.2 g/kg, showing a potential difference in efficiency according to diet.
• This needed further investigation, but the abstract was truncated. Thus, we cannot learn more of the researchers’ conclusions or other findings from this summary. Only the full article could reveal the remaining outcomes.