Influence of organic manganese supplementation on performance, digestibility, milk yield and composition of Afshari ewes in the transition period, and the health of their lambs

Introduction: Since the last two months of pregnancy (late pregnancy) constitute 75% of fetal growth, enriching the mother's diet can have positive consequences on the health and overall performance of the mother and children. Manganese functions in the immune system in different ways, including its activity in antioxidant pathways, its role in phagocytic activity, and maintaining the structural integrity of epithelial barriers against infection. Manganese deficiency can lead to dysfunction of innate and acquired immune systems in different species. Manganese toxicity is rarely observed. However, the main toxic effects attributable to this element are cardiotoxicity, hepatotoxicity, as well as deposition in specific components of the basal ganglia, and alteration of dopaminergic neuroenzyme activity. Diet enrichment with organic manganese increased feed consumption and improved dry matter digestibility in lambs. It has been documented that maternal manganese status is vital for ewe’s performance and the health of their newborn lambs. But, the required level and form of dietary manganese in ruminants are not well defined. Therefore, this study aimed to assess the influence of organic manganese supplementation on the performance, digestibility, milk yield and composition of Afshari ewes in the transition period, and the health of their lambs,
Materials and methods: For the present study, 24 single pregnant ewes were selected. They were kept in separate boxes (1 × 1 m²) with a concrete floor covered with straw during the experiment. Twenty-four lambs were born in three days from the experimental ewes. Forty-two days before lambing, the ewes were fed a diet rich in organic manganese. Water was also provided freely and separately. The experimental treatments included: 1. The first group (T1) was fed with the basal diet, 2. The second group (T2) was fed the basic diet enriched with 40 mg of organic manganese per kg DM (recommended by NRC), and 3. The third group (T3) received a basal diet enriched with 80 mg of organic manganese per kg DM (twice recommended by NRC). In this study, organic manganese (amino-manganese) contains an element of manganese and methionine, which are ionically connected. The diets of ewes were balanced using the NRC software. To calculate the weight change of the ewes, they were weighed five weeks before lambing, on the day of lambing, and five weeks after lambing. Also, the lambs were weighed on the day of birth and at the time of placental discharge. Feces and feed samples were collected in the last week for five days to test the digestibility of dry matter of ewes. They were determined in neutral detergent (NDF) by the Van Suest method, and crude protein and crude ash were measured according to the official Association of Analytical Chemists (AOAC) methods. The concentrations of fat, protein, lactose, and milk solids were measured by the Milkoscan device (MilcoscanTMS50-76510). A flame atomic absorption spectrometer model (Shimadzu-AA-670) with a wavelength of 279.5 nm was used to measure the magnesium concentration of milk. The feces of the lambs were evaluated daily. Stool scores were determined based on 1. Hard and consistent, 2. Soft and loose, 3. Loose and watery, 4. Watery with some blood, and 5. Watery with blood and mucus.
Results and discussion: At the end of the experiment, the weight and average feed consumption of ewes after delivery were influenced by organic manganese supplementation and showed a significant increase (P<0.05). While before delivery, there was no significant difference between the experimental treatments regarding the weight of the ewes (P>0.05). Also, the birth weight of the lambs and the time of placental discharge were not affected by the experimental treatments (P>0.05). The addition of different levels of organic manganese in the diet of ewes did not have a significant effect on digestibility parameters (dry matter, organic matter, crude protein, NDF, ADF, and ether extract) during the transition period (P>0.05). Supplementation of organic manganese in the diet of pregnant ewes during the transition period did not affect milk production (P>0.05). However, the amount of fat and solids in milk increased in the treatments with organic manganese supplementation, and this amount was higher in the animals that received 40 mg of organic manganese per kg DM (P>0.05). Also, the concentration of manganese in milk increased in animals that received organic manganese. In the present study, stool consistency improved under the effect of organic manganese supplementation. The number of lambs suffering from diarrhea and the average number of days suffering from diarrhea decreased significantly (P<0.05) due to the consumption of organic manganese supplements by the mother during the transfer period. Manganese is a nutrient associated with health and immunity. On the other hand, there is a close relationship between the antioxidant status of the body and the health of the animal because manganese plays a role in the structure of antioxidant enzymes such as superoxide dismutase (SOD).
Conclusions: According to the results of this study, organic manganese acts as a valuable and safe supplement that can be used to improve the ewe’s performance and the health of newborn lambs.