Effect of vitamin-mineral enriched Zeolite on milk yield, plasma Ca concentration and some reproductive disorders in early lactating dairy cows under heat stress

Background and objectives: Applying low-calcium to control milk fever have many problems in practice. Dietary Ca levels should be reduced by quantitative and qualitative methods such as limiting feed intake, which negatively affects the milk production and health of the cows. Anionic salts are also expensive and should be consumed before calving for a long period. It is also difficult to produce a homogeneous diet for selected cows in special section of a farm. In addition, add these salts to cows' diets reduces the palatability of the diet, decrease dry matter intake, conversely, increase negative energy balance and the concentration of non-esterified plasma fatty acids. Therefore, as an important goal of this research, it seems vital to introduce a method that solves the problems and have many advantages to improve productive traits and health related factors of fresh cows during a hot full stressed summer.

Materials and methods: Study was performed by 60 Holstein cows near calving in 3 experimental groups using a completely randomized statistical design with repeated measurements in time. Study was done in summer season, adaptation and experimental period were 15 and 45 days from -15 to +30 after calving time, respectively. Experimental diets including: 1) Low-Ca or control diet (Ca=0.44%), 2) Anionic diet (Ca=1%), 3) Control +enriched Zeolite diet. From second week after calving the cows were fed with a fresh milking diet The DCAD of diets were +100, -100, +100 mEq/kg DM respectively. The Anionic and Zeolite supplementation were used at level of 2.8 and 1.5% based on daily DMI of cows. Experimental traits were included milk production and compositions, total and ionized plasma calcium and some reproductive disorders.

Results: According to the results, consumption of DM and energy between diets were significantly different. Fat percentage of zeolite diet was higher than others but raw and corrected milk yield of anionic diet was the highest (P≤0.01). Plasma and ionized Ca concentration of zeolite diet were the same with two other diets at calving time but at 6, 12 and 24 hours after that were significantly higher than others (P≤0.01). The frequency of severe and subclinical hypocalcaemia was higher in control diet and older cows, but in zeolite diet was lower than others (P≤0.01). The highest BCS was for zeolite (2.98) and the lowest (2.86) for control diet (P≤0.01). The frequency of postpartum disorders (calving difficulty, retained placenta, endometritis, and abomasum displacement) was significantly lower in zeolite and anionic diets than control (P≤0.01). Highest percent of ssuccessful pregnancy, inversely, lowest percent of culled cows from herd observed in zeolits and anionic diets (P≤0.01).

Conclusion: According to the results, improved dry matter and energy consumption was observed in zeolite diet compared to anionic which had a direct effect on milk productive traits. Improved total and ionized Ca plasma concentrations during calving and after that and better control on hypocalcaemia and related problems in the herd, with highest BCS and a significant reduction in the frequency of postpartum disorders are of the advantages of zeolite diet. So the proposed method of calcium restriction using zeolite supplement seems to be successful and can be used as an alternative for common methods.