عنوان مقاله [English]
Introduction One of the most important additives in the past years has been antibiotics. Despite the beneficial effects of oral antibiotics on animal production and health, their use in animal nutrition for the production of bacteria resistant to various drugs (which may be hazardous to human health) has been controversial. The use of antibiotics has recently been banned due to bacterial resistance and chemical residues in meat and their side effects in humans Therefore, alternatives to the use of growth-promoting antibiotics should be identified and introduced to livestock breeders so that both efficiency and economic benefits are not diminished and consumer health concerns are eliminated. Much research has recently been done on the effects of plant essential oils as natural additives to improve rumen fermentation such as increased production of volatile fatty acids, reduced methane production, improved protein metabolism and increased feed utilization efficiency. Humans have used plants and their extracts for thousands of years .This experiment was conducted to investigate the effects of Carum copticum L. essential oil supplementation on nutrient digestibility and some blood and ruminal metabolites, milk production and milk compounds in Mahabadian goats.
Materials and Methods Treatments included: control diet (basal diet without essential oil), basal diet + 300 mg/kg of Carum copticum L. essential oil in the ration dry matter and basal diet + 600 mg / kg Carum copticum L. essential oil in the dietary dry matter. Treatments were provided by TMR. During the experimental period, the animals were kept individually and healthy. Each livestock had a separate mug and manger. The cages were thoroughly cleaned and washed before the animals were deployed. Goats always had access to fresh water all day long. Drinkers were also thoroughly cleaned once every two days. The study was conducted in three 21-day trial periods including 14 days of habituation and 7 days of vector record. All measurements taken are in the record stage. Experimental rations adjusted to dry matter, based on NRC recommendations with SRNS software version 1.9.4468. During the trial period, the amount of feed poured into the manger and the daily residue was recorded to calculate the dry matter intake. It was calculated on a daily basis, so that the amount of feed given was weighed daily, and the remainder of the feed was collected, weighed, and sampled twice a week. Daily milk production was recorded in goat milk production. Milk samples were collected weekly for two consecutive days to determine the composition of the milk produced, and its composition including the percentage of fat, protein, lactose and total solids was measured using (MilcoscanTMS50 model number 75610 Was taken). Blood samples were taken at 4 h after the morning meal to determine blood parameters. The blood samples were immediately transferred to the laboratory and centrifuged at 6,000 rpm for 7 minutes, and serum was stored in 1.5 ml microtubes in a freezer at -20 °C. Isolated serum for determination of albumin, creatinine, low-density lipoprotein, high-density lipoprotein, triglyceride, cholesterol, urea, total protein and glucose.
Results and Discussion Feed intake was not significantly different between treatments. Effect of experimental treatments on dry matter digestibility was not significant (P <0.05). Numerically, the highest digestibility was related to treatment of 300 mg/kg of Carum copticum L. essential oil and the lowest was related to 600 mg/kg treatment, and the effect of experimental diets on digestibility of crude protein, ether extract, organic matter, neutral detergent fiber and acid detergent fiber was not significant (p < 0.05). The effect of the experimental treatments on the amount of volatile fatty acids was not significant (p < 0.05) but the total amount of volatile fatty acids showed a significant decrease compared to the control. The effect of the experimental treatments on the amount of milk produced was not significant (p < 0.05). Effect of experimental treatments on milk fat and protein content was not significant (p < 0.05). As shown in the table, the experimental treatments had a significant effect on some blood parameters such as cholesterol, HDL, LDL, triglyceride, albumin, urea and creatinine (p < 0.05). Blood cholesterol significantly decreased with increasing dosage of essential oil Blood LDL concentration decreases with increasing dosage of essential oil in the diet. Blood HDL increased significantly with increasing essential oil content.
Conclusion In general, the results of this study showed that the addition of Carum copticum L. essential oil to Mahabadian goat’s diet did not have a significant effect on milk yield, production and composition but it decreased total rumen volatile fatty acids, serum cholesterol, triglyceride and LDL concentrations. However, further research is needed.