Abstract
Two experiments were conducted to examine the influence of kaolinite clay supplementation (0%, 1%, or 2% diet dry matter [DM] basis) on characteristics of digestion (Trial 1) and growth performance (Trial 2) in calf-fed Holstein steers fed a finishing diet. In Trial 1, 6 Holstein steers (539±15 kg) with ruminal and duodenal cannulas were used to evaluate treatment effects on characteristics of digestion. Kaolinite clay supplementation decreased total tract DM digestion (linear effect, p<0.01) without effects (p≥0.10) on site and extent of digestion of organic matter, neutral detergent fiber, starch and N, or ruminal microbial efficiency. There were no treatment effects on ruminal pH, volatile fatty acids molar proportions or estimated methane production. In Trial 2, 108 Holstein steers (132.4±5.6 kg) were used in a 308-d study to evaluate growth performance and carcass characteristics. There were no treatment effects (p>0.10) on average daily gain (ADG) and gain efficiency (ADG/dry matter intake). Kaolinite supplementation tended (linear effect, p = 0.08) to increase dietary net energy (NE) during the initial 112-d period. However, the overall (308-d) effect of supplementation dietary NE was not appreciable (p>0.20). However, due to the inertness of kaolinite, itself, the ratio of observed-to-expected dietary NE increased with kaolinite supplementation. This effect was more pronounced (linear effect, p 0.03) during the initial 224 d of the study. Overall (308 d), kaolinite supplementation tended to increase (linear effect, p = 0.07) dietary NE by 3% over expected. Kaolinite supplementation did not affect carcass weight, yield grade, longissimus area, kidney, pelvic and heart fat, and quality grade, but decreased (linear effect, p = 0.01) dressing percentage. It is concluded that kaolinite supplementation up to 2% of diet DM may enhance energetic efficiency of calf-fed Holstein steers in a manner independent of changes in characteristics of ruminal and total tract digestion.
Highlights
Due to the inertness of kaolinite, itself, the ratio of observed-to-expected dietary net energy (NE) increased with kaolinite supplementation
It is concluded that kaolinite supplementation up to 2% of diet DM may enhance energetic efficiency of calf-fed Holstein steers in a manner independent of changes in characteristics of ruminal and total tract digestion. (Key Words: Kaolinite, Feedlot, Supplementation, Cattle, Growth, Digestion)
(132.4±5.6 kg) were used in a 308-d experiment to evaluate the influence of kaolinite clay supplementation on growth performance, dietary net energy (NE), and carcass characteristics
Summary
Clay minerals (bentonite, kaolinite, zeolite) are ubiquitous in nature. Unique structural properties lend to their usefulness as feed additives. Kaolinite supplementation tended (linear effect, p = 0.08) to increase dietary net energy (NE) during the initial 112-d period. Kaolinite supplementation did not affect carcass weight, yield grade, longissimus area, kidney, pelvic and heart fat, and quality grade, but decreased (linear effect, p = 0.01) dressing percentage.
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