The Effect of Using Different Probiotics on the Performance, Digestibility of Nutrients, Feces Score, Blood Parameters and Skeletal Indices of Suckling Holstein's Calves

Rearing suckling calves is critical for dairy herd productivity, but this period often involves digestive disorders, poor nutrient digestibility and loose faeces, which impair growth. Probiotics are promising, yet their comprehensive effects on blood parameters and skeletal development in suckling Holstein calves remain unclear.

This study aimed to evaluate the effects of single and multi-strain probiotics (Saccharomyces boulardii, Bacillus subtilis and Lactobacillus) on growth performance, faecal score, nutrient digestibility, blood metabolites and skeletal development in suckling Holstein calves.

In this study, 36 Holstein female calves aged 7 ± 3 days with an initial body weight of 44.7 ± 2 kg were assigned to six treatments with six replicates in a completely randomized design for 45 days. Experimental treatments were as follows: (1) Control diet without probiotics; (2) diet containing S. boulardii (BS); (3) diet containing B. subtilis (B); (4) diet containing Lactobacillus (L); (5) diet containing S. boulardii + Lactobacillus; and (6) diet containing S. boulardii + Lactobacillus + B. subtilis. Probiotics were mixed with milk and administered once daily at a rate of 5 g per calf.

Probiotic supplementation significantly affected 28-day body weight, weight gain from Days 1-28, final body weight, and overall daily weight gain (p < 0.05). Body weight change, total dry matter intake, daily starter intake, feed conversion ratio and dry matter intake were also improved by probiotic supplementation (p < 0.05). Final body weight in the control group was lower than in all probiotic-treated groups (p < 0.05). Probiotic supplementation significantly improved faecal consistency score, with the lowest score observed in calves receiving B. subtilis (p < 0.05). Digestibility of dry matter, organic matter, crude fat and neutral detergent fibre increased with probiotic supplementation (p < 0.05). Blood biochemical parameters were not significantly affected by probiotic treatments. Skeletal indices were improved in probiotic-treated calves compared to the control group (p < 0.05).

Probiotic supplementation improved growth performance, faecal score, nutrient digestibility and skeletal development of suckling calves. Among the evaluated treatments, B. subtilis showed the most consistent positive response under the conditions of this study, although combined probiotic treatments also improved several parameters compared to the control.