The effect of body condition score and supplementation of dietary rumen-protected niacin and choline chloride during transition period on metabolic status of Murciano Granadina dairy goats

Introduction: The transition period in dairy goats refers to the period of three weeks before and three weeks after parturition. During this period, the increase in nutritional requirements as a result of the increased nutrient requirements resulting from the exponential growth of on the one hand, and the reduction in feed intake due to the decreased nutrient uptake caused by the increased uterine volume on the other hand, exposes the animal to negative energy balance and various metabolic abnormalities such as pregnancy toxemia. Therefore, finding alternatives that can reduce the consequences of negative energy balance will lead to an improvement in metabolic status and animal health. Additives involved in energy metabolism, such as rumen-protected niacin and choline chloride, can mitigate the negative effects of negative energy balance in the transition period due to their contribution to lipid metabolic pathways and gluconeogenesis, thus leading to a strengthening of the animal's metabolic status. Objective: This research was conducted to evaluate the effect of body condition score and supplementation of rumen-protected niacin and choline chloride during the transition period on blood parameters of Murciano Granadina dairy goats. Material and methods: During the transition period (21 days prepartum and 21 days postpartum), seventy-two multiparous pregnant Murciano-Granadina goats that were previously estrous-synchronized with CIDR and PMSG hormone were equally allocated (n= 12) to one of the following six experimental diets based on BCS in a randomized complete block design: 1) LBC: dry goats with 3≤BCS≤3.5 and fed the basal diet; 2) HBC: dry goats with BCS>3.5 and fed the basal diet; 3) HBC+ Ni: dry goats with BCS>3.5 and fed the basal diet plus 4.7 g of rumen-protected niacin; 4) LBC + Ni: dry goats with 3≤BCS≤3.5 and fed the basal diet plus 4.7 g of rumen-protected niacin; 5) HBC + Cho: dry goats with BCS>3.5 and fed the basal diet plus 16 g of rumen-protected choline chloride and 6) LBC + Cho: dry goats with 3≤BCS≤3.5 and fed the basal diet plus 16 g of rumen-protected choline chloride. he commercial brand of rumen-protected choline chloride used in this experiment was VETACHOL and contained 25% coated choline, and the commercial brand used for rumen-protected niacin was NIAPASS and contained 50% coated nicotinic acid. The experimental diets were formulated according to the requirements recommended by NRC (2007) and using SRNS (2007) software and were offered in four meals. During the experimental period, the difference between the amount of feed offered and rejected was recorded daily to calculate the dry matter intake of the goats. Sampling of feeds was done weekly to determine the chemical composition of feed such as dry matter, ash, crude protein, NDF, fat, calcium, and phosphorus content. Blood samples were collected from the experimental animals on the 130th, 137th, and 143rd day of pregnancy and on the 7th and 14th day after kidding for determination of glucose, triglyceride, cholesterol, VLDL, total protein, albumin, and urea nitrogen levels using Pars Azmun diagnostic kits via spectrophotometry. All statistical analyses were performed with a randomized complete block design using SAS v.9.3 software. Results and discussion: On the 137th and 143rd days of pregnancy, blood glucose levels were higher in goats fed rumen-protected choline chloride than in those fed rumen-protected niacin and the control groups (P < 0.01). On day 143 of pregnancy and at the time of parturition, administration of rumen-protected choline chloride resulted in an increase in triglyceride and VLDL concentrations compared with the other nutritional treatments (P < 0.01). The increase in VLDL concentration when taking rumen-protected choline chloride may be due to the fact that RPC increases the synthesis of phosphatidylcholine and leads to the export of VLDL from the liver, thereby improving lipid metabolism (Lima et al. 2010). During the last week of pregnancy, the blood cholesterol concentration of goats consuming the rumen-protected choline chloride was higher than in the other groups (P < 0.01), but did not differ from the control group with a high body score. In the first week after kidding, goats that did not receive any supplements had lower cholesterol concentrations than other experimental groups in both groups of body condition scores (P<0.01). The results also showed that the amount of total protein and blood albumin of goats during the transition period was not affected by the nutritional treatments and body condition scores (P > 0.05). The fact that the albumin and total protein concentrations of the studied goats did not change during the transition period may indicate that the rations used in the experiment provided sufficient protein to the studied animals, because despite the significant differences between treatments in terms of blood concentration, no significant difference was observed in total protein and albumin levels. On day 14 postpartum, the use of rumen-protected niacin in goats with high body condition scores resulted in higher urea concentrations compared with the LBC, HBC + Cho, and LBC + Cho treatments (P < 0.01). The increase in blood urea concentration as a result of rumen-protected niacin intake may be related to the coenzyme NADH, which is required for urea biosynthesis to provide amino nitrogen via aspartate (Harmeyer and Kolnkrichen 1989). Conclusion: In general, the results of this study showed that the use of rumen-protected choline chloride at the rate of 16 g/head/day in the diets of Murciano Granadina dairy goats with 3≤BCS≤3.5 or BCS > 3.5 during the transition period improved the metabolic status of the goats by increasing the amount of glucose, VLDL, triglyceride, and cholesterol, especially one week before parturition, whereas the beneficial effect of protected niacin supplementation was less evident. Therefore, it is recommended to use this additive during the transition period of Murciano Granadina dairy goats to improve their metabolic status and prevent metabolic disorders.