Effect of Different Levels of Probiotics and Organic Acid Supplements on Performance, Skeletal Growth, Nutrition Activity, Blood and Immune Metabolites in Holstein Calves

Calf breeding has been one of the most important and sensitive management programs in cattle farms. Therefore, using the right nutrition strategies for their improved growth and health is very important. For this reason, antibiotics have long been used in many countries to increase the growth of livestock due to their inhibitory effect on harmful bacteria in the gastrointestinal tract. In the last decades antibiotics were used for stimulating growth and increasing viability in calves, because of improving antibiotic resistance finding new techniques for improving growth and viability and reducing weaning weight is necessary. Adding supplemental levels of probiotic and organic acids can increase the immune system and improve health of calf.

In this study, the effects of different levels of probiotic and organic acids additive were investigated on blood metabolites, immune response and health of Holstein calves.

In order to determine the effects of different levels of probiotic and organic acids on the performance, skeletal growth and feeding activity of infant calves, the experiment was conducted using 36 Holstein calves with a mean weight of 36 kg ± 2 in a completely randomized design with nine treatments and four replicates. The experiment lasted for 75 days in Moghan Agro-Industrial Company located in Parsabad city, Ardebil province. Treatments included: 1. basal diet without additive (control), 2. basal diet containing 2 g probiotic additive, 3.basal diet containing 3 g probiotic, 4. basal diet containing 3 g organic acid, 5. basal diet containing 4.5 g organic acid, 6. basal diet containing 2 g of probiotic and 3 g of organic acid, 7. basal diet containing 2 g of probiotic and 4.5 g of organic acid, 8. basal diet containing 3 g probiotics and 3 g of organic acid and 9. basal diet containing 3 g probiotic and 4.5 g organic acid. The study evaluated feed intake, body weight gain, feed conversion ratio, skeletal growth, nutrition behavior, blood parameters, immune response and the calves health state. The test results were analyzed in a completely randomized design with SAS statistical software version 9.1.

The results showed that experimental diets had a significant effect on feed intake and daily gain, blood glucose and cholesterol and improved the immune system and health status of calves (p <0.05). In contrast, the experimental diets do not have a significant effect on the final weight and feed conversion ratio. This study also showed that the addition of probiotic, organic acid and the combination of these additives did not affect skeletal growth and feed intake activity of Holstein calves. Experimental treatments at 60 days and the whole period had a significant effect on feed intake. In general, probiotics increase food intake through their effects on the processes of digestion and absorption of nutrients. The average daily weight gain in the first, second and whole months of the period was affected by experimental diets but the overall effect of treatments in time periods was not significant. Blood glucose concentrations were increased in calves receiving treatment 5, which could be attributed to the created suitable environment in the intestinal tract due to the consumption of organic acids, which may have contributed to the digestion and absorption of more nutrients and As a result, it increases the blood glucose levels. Experimental diets had a significant effect on the white blood cell percentage in both sampling times (45 and 75 days). In general, the improvement of the immune system by probiotics is done through three ways of increasing general antibodies, increasing macrophage activity and increasing the production of local antibodies on the mucosal surface of tissues such as the intestinal wall. The effect of organic acids on the immune system is still largely unknown, but in general it can be said that organic acids improve digestion and absorption of nutrients as well as reducing harmful bacteria and help the immune system improvement.

based on the obtained results dietary treatments do not have any adverse effect on calves' performance. Moreover, it can be concluded that feeding probiotic and organic acid to the calves could have positive effects on animal performance and health state, so supplementing the diets by these substances is a good mean to improve the calves’ growth.