精油組合物對豬隻糞便臭味與血漿健康指標的影響

Abstract

腸道的健康影響著動物整體的消化、吸收與生長，而腸道菌群與宿主維持共生的關係，當宿主受到環境及飲食的變化，會影響腸道菌群及腸道型態，續而影響宿主的健康。離乳是豬隻出生後首先面臨的挑戰，此時常會因飼糧、併欄及環境的變化，造成腸道菌相改變，進而影響豬隻的生長。而飼糧及環境轉變帶來的壓力，在豬隻的生命週期的各個階段也持續發生，除了使生長表現低落外，消化吸收功能不彰也會使過多未消化的營養物質進入後腸中，增加微生物發酵利用並產生較多氨、吲哚、酚類及揮發性脂肪酸等臭味物質的機會。 精油是由植物萃取的揮發性有機化合物，目前已有許多研究證實具有抗微生物、抗發炎及抗氧化的能力，可改善動物的健康，並且能有效減少豬隻排泄物中的臭味物質，減少對環境造成的負面影響。本試驗欲找尋適合用於臺灣豬隻飼糧中的精油種類與比例，以探討其降低豬隻臭味排放及改善健康的潛力。 首先，在體外試驗中，將carvacrol、thymol及cinnamaldehyde三種精油以不同濃度組合添加於飼糧中，模擬豬隻消化及後腸發酵，欲找出能改善臭味排放的精油濃度，發現當飼糧中含有cinnamaldehyde 10 ppm、thymol 20 ppm (2EO組)，以及cinnamaldehyde 20 ppm、thymol 20 ppm及carvacrol 200 ppm (3EO組) 時，可顯著減少發酵上清液中尿素酶與蛋白酶活性 (p < 0.05)，降低氨態氮、對甲酚、吲哚及糞臭素濃度 (p < 0.05)，並顯著具有較低的發酵潛能及發酵速率 (p < 0.05)，因此以此精油種類及濃度組合進行後續動物試驗。 動物試驗中，以離乳豬及生長豬分別進行六週及四週試驗，結果顯示，無論是2EO或3EO組，皆不會對豬隻的生長表現產生負面影響，且3EO組能顯著提升生長豬的消化率及氮消化率 (p < 0.05)。與對照組相比，2EO組可顯著減少生長豬糞便中的總氮排放量、氨態氮、對甲酚、吲哚、糞臭素及血漿中尿素氮濃度 (p < 0.05)，並降低糞便中的尿素酶、蛋白酶活性，促進血漿中的抗氧化能力及減少促炎細胞激素IL-6濃度 (p < 0.05)。3EO組則可顯著減少離乳豬糞便中的氨態氮及血漿中的尿素氮濃度 (p < 0.05)，並顯著降低生長豬糞便中的氮排放量、氨態氮、對甲酚、吲哚、糞臭素、血漿中尿素氮濃度及糞便中尿素酶、蛋白酶活性 (p < 0.05)，並能顯著提升此兩階段豬隻血漿中的抗氧化能力，減少脂質過氧化物MDA及IL-6濃度 (p < 0.05)。同時，從試驗中生長豬糞便揮發性脂肪酸的測定結果，可發現使用的兩種精油組合，都在不增加總揮發性脂肪酸的情況下，顯著增加丁酸的比例 (p < 0.05)，推測在增加上皮細胞能量來源的同時，並未產生更多的臭味來源。 綜合體外試驗及動物試驗的結果，可發現對於對甲酚、吲哚、糞臭素等臭味物質的排放，2EO組顯著較其他處理組具有較佳的減量效果 (p < 0.05)，但是根據生長表現及消化率的結果，顯示有可能對豬隻的生長具有負面的影響，而3EO組則能在顧及生長表現時，達到減少豬隻臭味物質排放的目的。

Intestinal health affects digestion, absorption and growth of the animal. Environmental factors and diets associate with alterations in the gut microbiota and morphology, usually impact host health and sometime induce diseases. Weaning is the first challenge a pig faces after birth, frequently accompanied with dysbiosis of gut microbiota, reduced feed intake, and negative effects of growth performance. The multiple stresses come from changes in diets and environmental factors keep occurring in pig’s life cycle. In addition to deteriorating growth performance, poor digestion and absorption also cause excessive undigested nutrients to enter the hindgut, increase microorganism fermentation, thus producing more odor substances such as ammonia, indole, phenols and volatile fatty acids. Essential oils are aromatic, volatile organic compounds extracted from plant. Several studies summarize the effects of essential oil on anti-microbiota, antioxidant and reducing inflammation. Essential oils promote animal health, reduce odor substances of pig waste, and decrease negative effects to environment. The objectives of this study are to find out the optimal combination of essential oils suitable for pig industry in Taiwan, and to evaluate the possibility of odor reduction and pig health promotion. First, the in vitro trial was applied to simulate pig digestion and hindgut fermentation. Various dosages of carvacrol, thymol and cinnamaldehyde were added to growing pig diets to find out the optimal combination of essential oils for reducing odor emission. It was found that when the diet contained cinnamaldehyde 10 ppm, thymol 20 ppm (2EO treatment), and cinnamaldehyde 20 ppm, thymol 20 ppm and carvacrol 200 ppm (3EO treatment), fecal activity of urease and protease was significantly reduced (p < 0.05). These two treatments decreased the fecal emission of odor substances, including ammonia nitrogen, p-cresol, indole and skatole (p < 0.05). A significantly lower fermentation potential and fermentation rate were observed in these two treatments (p < 0.05). Therefore, these two treatments were used in follow-up animal experiments. In the animal experiment, there were six and four weeks respectively lasted in weaning and growing pig trial. The results showed that essential oils did not exist any negative impact on the growth performance of pigs, and 3EO significantly improved the growth performance, digestibility, and nitrogen digestibility of growing pigs. (p <0.05). Compared with the control group, 2EO significantly reduced total nitrogen emissions, ammonia nitrogen, p-cresol, indole, skatole, the activity of urease and protease in the feces of growing pig (p < 0.05), decreased the concentration of urea nitrogen and pro-inflammatory cytokine IL-6 in the blood as well as enhanced antioxidant capacity in growing pigs (p < 0.05). The 3EO significantly reduced the fecal concentration of ammonia nitrogen and the blood urea nitrogen in weaning pig (p <0.05). The 3EO significantly reduced the nitrogen emissions, ammonia nitrogen, p-cresol, indole, skatole, activity of urease and protease in feces, (p < 0.05), as well as significantly decreased concentration of blood urea nitrogen, MDA and IL-6 meanwhile improved the antioxidant capacity in the blood of growing pigs (p < 0.05). Essential oils significantly increased the ratio of butyric acid (p < 0.05) without affecting the amount of total volatile fatty acids, suggesting more energy supply to epithelial cells and less contribution to odor emissions. Combining the results of in vitro and in vivo trial, we found that 2EO treatment have more effects on reduction of odors emission such as p-cresol, indole, skatole, however, it is more likely to have a negative impact on pig growth. The 3EO treatment could take into account the growth performance and pig health while reducing odor emission.