Effect of olive pomace on digestibility, blood biochemical parameters and milk production and composition of dairy Buffalo

Since, feeding in animal husbandry is one of the most critical and costly issues, therefore should focus on cheap resources like agricultural wastes which provide adequate nutrients for livestock. Olive pomace is a residue of the oil extraction of olive fruit, which after drying can be used as a by-product in animal feed. Olive pomace contains high lignin (32% DM), cellulose and hemicellulose (Sadeghi et al., 2009). Raw olive pomace contains high amounts of 16 and 18 fatty acids; and about 96% of olive pomace fatty acids include linoleic acid and oleic acid (Nazari et al., 2008). Olive pomace is containing anti-nutritional components such as phenolic compounds and tannins (0.58 to 1.1 g/kg DM), and it may have adverse effects on livestock (Molina et al, 2003). Feeding dairy ruminants with non-core olive cake containing tocopherol, retinol and phenols can cause positive changes on milk quality, and improved oxidative stability of milk (Pauselli et al, 2007). Most of buffalo breeders use wheat flour in buffalo diet. Using wheat flour, can destroy the rumen microbial population and as an important part in human foods, increases costs. However, there is no research on wheat flour replaced with olive pomace in buffalo nutrition. Therefore, this study was conducted to explore the effect of olive cake on digestibility, blood biochemical parameters and production performance of Khuzestani dairy Buffalo.

Fifteen dairy buffaloes average 4 years, average body weight 570 kg and 2 parities were used in a completely randomized design with 3 treatments and 5 repetitions. Experimental treatments were included 0%, 7.5%, and 15% olive pomace substituted with wheat flour, which fed two times daily for 45 days in a completely randomized design. Diets were formulated according to the NRC. The olive pomace used in this study dried by air drying. The pomaces were stirred and mixed several times daily. The crude protein, metabolizable energy, neutral detergent fiber, acid detergent fibers, and fat of olive pomace were 6.5%, 2.65 Mk / kg DM, 56, 45, and 9 %, respectively.At the end of the experiment, feed intake, nutrient digestibility, production performance and blood parameters were measured. The diets were prepared completely mixed and given daily at 7:00 and 17:00. Fresh water was also available to them. The combination of control diet consisted of corn silage, wheat straw, olive cake, wheat flour, wheat bran, rice bran, mineral supplement and vitamins, limestone. Milking was done every day in the morning and evening and milk production was recorded. Milk scanner was used to measure milk protein, fat, and lactose. The milk pH determined by using pH papers or electrical pH meters; and milk solids and non-fat solids (SNF), by lactometer.Also, blood samples were taken from all buffaloes at the end of the period, 3 to 4 hours after morning intake and blood metabolites determined. For apparent digestibility of the diets, during three consecutive days, buffalo feces were collected. Also, sampling of feed residuals in the last three days of the period was weighed. Then, the digestibility of organic matter, dry matter, crude protein, crude fat, acid detergent fibers and neutral detergent fibers were measured.The obtained data were analyzed using the General Linear Model procedure of the SAS. A comparison of the mean was made with Duncan. The model of this design was a completely randomized design with three treatments, and each treatment includes five replications based on the statistical model: Yij= µ + Ti+ eij. Also, repeated data per time were analyzed based on the mixed statistical model. Yci = µ + Tc + Ɛic + (T*P)ik.

Milk fat and SNF increased in experimental treatments at the end of the period (P<0.05). However, milk production, protein, acidity, density and pH of milk were not affected by the experimental treatments (P>0.05). Milk production increased by using dried olive kernels in dairy buffaloes (Terramoccia et al., 2013). Inclusion of unsaturated fatty acids often reduces the saturated fatty acids of milk. Also, high fat in olive pomace can be a major reason for high percentage of milk fat in the olive pomace treatment compared to control (Chilofalo et al. 2003). Also, the concentration of blood parameters was not affected by experimental diets. But, blood cholesterol in 7.5% olive cake increased and the concentration of alkaline phosphatase enzyme increased by 15% olive cake compared to the other treatments (P<0.05). Obeidat (2017) reported that adding olive pomace to the diet of Awasi lambs had no effect on blood parameters (glucose, blood urea nitrogen, aspartate aminotransferase and alanine aminotransferase). But Hashish and Al-Sameh (2012) declared that saturated fatty acids in olive pomace can increase the concentration of saturated fatty acids and blood cholesterol. Other researchers also concluded that with the increase in dietary fat concentration, blood cholesterol increased (Bhatta et al., 2011). Nutrient digestibility was not affected by experimental treatments (P>0.05). Using olive pomace up to 20% instead of barley in Lori lambs increased microbial protein production in the rumen. Also, olive pomace in the Dalagh sheep diet increased feeding efficiency and carcass weight; and reduced production costs up to 66% (Samadi, 2009). The use of olive pomace in Awasi lambs, did not influence dry matter intake, digestibility of crude protein, neutral detergent fiber and acidic detergent fiber (Obeidat, 2017).

According to the recent study, replacing wheat flour with olive cake had no negative effect on production, blood parameters and digestibility of nutrients in dairy buffaloes, and due to the reasonable price of olive cake; replacing olive cake up to 15% with wheat flour in the diet of dairy buffaloes is recommended.