Effects of Spent Bleaching Clay Supplementation on Ruminal Fermentation and Digestibility in Holstein Dairy Cows

식용유 정제 폐백토(Spent Bleaching Clay)의 급여가 반추위 발효특성과 사료 이용률에 미치는 영향

These studies were conducted to evaluate the feasibility of spent bleaching clay (SBC) as a feed resource for ruminants. Three Holstein dairy cows, surgically fitted with ruminal cannula, were used in a $3{\times}3$ Latin Square design. Dietary treatments were 1) basal diet, 2) basal diet plus 2% of SBC and 3) basal diet plus 4% of SBC. Rumen fluid was sampled at 0, 3, 6, 9 and 12 hours following the start of the morning feeding. Nylon bags containing experimental diets were used to determine ruminal nutrient disappearance at 0, 3, 6, 12 and 24 hours. The values of ruminal pH in cows receiving 4% of SBC was lower than those of the control and 2% SBC supplement. The $NH_3-N$ concentration in the rumen was higher at the 3 hour than for cows of control and 2% of SBC supplement. Total VFA concentrations in the rumen were not affected by the addition of SBC. Dry matter and organic matter disappearance in the rumen was lower at the 6 hours than the control and 2% SBC treatment, but no difference at the end of the 24 hour.

본 시험은 Spent bleaching clay(SBC) 첨가에 따라 반추위내의 발효특성과 이용율을 조사하기 위하여 Fistula가 장착된 홀스타인 3두를 공시하여 반추위내 발효성상을 조사하였다. 반추위내 pH 변화는 대조구와 SBC 2% 첨가구간에는 차이가 없었으나, SBC 4% 첨가에 의하여 낮아지는 경향이 인정되었다. 반추위내 $NH_3-N$의 함량은 SBC 4% 첨가구가 대조구와 SBC 2% 첨가구에 비하여 사료 급여 후 3시간째까지 높은 경향을 나타냈으나 이후 3처리구는 유사한 경향을 나타내었다. 한편 SBC의 첨가수준에 관계없이 반추위내 VFA의 함량은 변화가 없는 것으로 나타났다. 반추위내 건물 및 유기물 손실율은 SBC 4% 첨가구가 대조구 및 SBC 2% 첨가구에 비해서 배양초기에는 낮아지는 경향을 보였으나 이후 4처리간 차이는 인정되지 않았다.