Effects of Different Levels of Crude Protein on Physiological Responses, Litter Performance, Blood Profiles, and Milk Composition and Odor Emission in Lactating Sows

Abstract

본 연구는 포유돈 사료 내 조단백질 수준이 모돈 및 자돈의 생리적인 변화, 포유능력, 혈액성상, 돈유성분 및 악취 발생에 미치는 영향을 조사하여 포유돈 사료 내 조단백질의 수준을 규명하기 위해 수행되었다. 본 실험은 평균 체중(BW)이 238.0±4.65kg, 평균 등지방 두께가 20.95±1.38mm, 평균 산차가 4.65±0.44인 인 2 원교잡종 (Yorkshire × Landrace) F1 모돈 48 두를 공시하여 6처리 8반복, 반복 당 1 두씩, 체중과 등지방 두꼐에 따라 완전임의배치법 (CRD; Completely randomized design)으로 구배치하여 실험을 수행하였다. 실험의 처리구는 포유돈 사료 내 조단백질 첨가수준에 따라: 1) CP15, 2) CP16, 3) CP17, 4) CP18,5) CP19, 6) CP20으로 나뉘었다. 실험결과, 사료 내 조단백질 첨가 수준에 따라 분만 24시간이내 및 포유 21일령의 체중 및 등지방 두께에서 처리구 간 유의적인 차이가 나타나지 않았다 (P>0.05). 또한, 총 산자 수, 사산두수, 생존자돈 수, 포유개시 두수, 이유두수, 복당 생시체중 및 복당 이유체중에서 처리구 간 유의적인 차이가 나타나지 않았다 (P>0.05). 돈유 중 카제인 함량은 사료 내 조단백질 수준이 증가함에 따라 선형적으로 감소하였다 (linear, P=0.03). 포유 자돈의 혈액 성상에서 유의적인 차이가 나타나지 않았으며 (P>0.05), 포유 21일령 모돈 혈액 중 총 단백질과 BUN 수치에서 조단백질 수준이 증가할수록 선형적으로 증가하였다 (linear, P=0.01; linear, P=0.01). 조단백질 첨가수준이 증가함에 따라 아민, 암모니아 및 황화수소를 포함한 악취 발생이 선형적으로 증가하였다 (linear, P=0.01). 결론적으로, 사료 내 조단백질 수준이 20%에서 15%까지 감소하여도 모돈의 체형변화, 번식성적 및 포유자돈 성장에 부정적인 영향을 미치지 않으며, 체내 단백질 이용율을 개선하여 악취 발생을 줄일 수 있는 것으로 사료된다.

Dietary protein plays a very important role in maintaining healthy growth and normal immune function in animals. Excessive protein increases the cost of feed and the burden on the farm, and increases nitrogen emissions in manure and urine, which contribute to environmental pollution. Dietary protein level is an important factor influencing nitrogen utilization and lactation performance of sows. Additionally, variation in sow intake during different seasons may also affect protein intake, nitrogen utilization and reproductive performance of lactating sows. Therefore, this experiment was conducted to investigate the effects of dietary crude protein level on physiological response, reproductive performance, blood profile, milk composition and odor emission of lactating sows in summer. A total of 48 F1 multiparous sows (Yorkshire × Landrace) with average body weight (BW) of 238.0 ± 4.65 kg, average backfat thickness of 20.95± 1.38mm, and an average parity of 4.65 ± 0.44 was used in a 3wk trial at a research farm located in Eum seong, Korea. All sows were allotted to one of six treatments considering body weight (BW), backfat thickness, and parity in completely randomized design (CRD) with 8 replicates. All experimental diets for lactating sows were formulated based on corn soybean meal. Treatments are as followed: 1) CP15: corn‒soybean-based diet containing 15% CP, 2) CP16: corn‒ soybean-based diet containing 16% CP, 3) CP17: corn‒soybean-based diet containing 17% CP, 4) CP18: corn‒soybean-based diet containing 18% CP, 5) CP19: corn‒soybean-based diet containing 19% CP, and 6) CP20: corn‒soybean-based diet containing 20% CP. All other nutrients in experimental diets were formulated to meet or exceed the NRC requirements (2012). There were no significant differences in body weight, backfat thickness and average daily feed intake of lactating sows between dietary crude protein levels throughout the trial period. Similarly, there was no significant difference in the effect of increasing dietary crude protein level on the number of live births, average litter weight and average piglet weight of sows. Casein content in milk decreased linearly with increasing crude protein level in the diet (P<0.05). The increase of protein level in the diet did not have a significant effect on the blood biochemical parameters of piglets. The effect of changing the crude protein levels in the feed on triglyceride, creatinine and glucose concentrations in the blood of sows was no significantly different. However, as the crude protein level increased, there was a linear increase in urea nitrogen and total protein content levels in the blood of lactating sows (Linear, P=0.01). The concentrations of odor gases, including amine, ammonia and hydrogen sulfide, increased linearly when sows were fed diets with higher levels of the dietary CP (Linear, P=0.01). Increasing the protein level in the diet did not improve the performance of lactating sows and piglets. Consequently, this experiment demonstrated that crude protein level of 15% in sow diet help to reduce the odor gas emissions from manure as well as feed cost of sows without any detrimental effects of reproductive performance of sow.