University of Tehran Press Journal of Animal Production, Print ISSN: 2008-6776., Online ISSN: 2382-994X 2008-6776 28 2 2026 06 22 The effects of probiotic and biochar supplementation on performance, nutrient digestibility and blood parameters in Holstein suckling calves The effects of probiotic and biochar supplementation on performance, nutrient digestibility and blood parameters in Holstein suckling calves 167 180 106800 10.22059/jap.2026.405678.623878 FA Mahdi Nasrabadi Department of Animal Science, Faculty of Agriculture, Bu-Ali Sina University, Hamedan, Iran. E-mail: m.nasrabadi@agr.basu.ac.ir 0000-0002-7552-0858 Khalil Zaboli Corresponding Author, Department of Animal Science, Faculty of Agriculture, Bu-Ali Sina University, Hamedan, Iran. E-mail: zaboli@basu.ac.ir 0000-0001-9887-2736 Journal Article 2025 11 05 Objective: The suckling calf is particularly susceptible to digestive and respiratory disease because of its immature immune system and increased mortality, making it one of the major challenges of the livestock industry. The nutritional strategy to enhance the performance of suckling calves by supplementing their diet with feed additives, such as probiotic and biochar, was evaluated in this study. Method: Twenty-eight female newborn Holstein calves (41.2 ± 3.8 kg) were used in a 2×2 factorial arrangement within a completely randomized design over a 70‑day experimental period. Experimental treatments were as follows:1- basal diet without additive (control), 2- basal diet with 2 g/day of probiotic, 3- basal diet with 1% biochar and 4- basal diet with 2 g/day of probiotic plus 1% biochar. The basal diet was formulated with a 10:90 forage-to-concentrate ratio to meet nutrient requirements. Water and starter feed were provided ad libitum throughout the experiment. Feed intake was recorded daily, body weight and skeletal growth changes were assessed every two weeks. Blood samples were collected on days 0 (birth time), 35 and 70, and fecal samples were collected to evaluate diet digestibility in the last week of the experiment from all calves. All calves were observed for three days at the end of the experiment to record their feeding behaviors (standing, lying, eating, and ruminating) and non-feeding behaviors (licking, sucking, and chewing on environmental objects). Results: Results indicated that calves that were supplemented with dietary biochar had significantly higher starter feed intake and weaning body weight compared with the non‑biochar groups (P<0.05). Wither height, hip height and abdominal circumference of the calves also increased with biochar supplementation (P<0.05). Concurrent supplementation with probiotic and biochar (treatment 4) further enhanced wither height and hip height (P<0.05). probiotic and biochar supplementation improved apparent digestibility of organic matter and crude protein (P<0.05), respectively, whereas the digestibility of other nutrients was unaffected by experimental treatments. Biochar supplementation also increased blood glucose concentration (P<0.05). Dietary treatments did not significantly affec any of the feeding behaviors. Interaction effects of probiotic and biochar were not significant on any of the parameters measured in this study. Conclusions: Overall, dietary supplementation with biochar, either alone or in combination with probiotic, showed significant positiv effects on performance, skeletal growth indices, and digestibility of nutrients in suckling calves, suggesting that biochar may be used as a functional feed additive to support early-life health and productivity. Objective: The suckling calf is particularly susceptible to digestive and respiratory disease because of its immature immune system and increased mortality, making it one of the major challenges of the livestock industry. The nutritional strategy to enhance the performance of suckling calves by supplementing their diet with feed additives, such as probiotic and biochar, was evaluated in this study. Method: Twenty-eight female newborn Holstein calves (41.2 ± 3.8 kg) were used in a 2×2 factorial arrangement within a completely randomized design over a 70‑day experimental period. Experimental treatments were as follows:1- basal diet without additive (control), 2- basal diet with 2 g/day of probiotic, 3- basal diet with 1% biochar and 4- basal diet with 2 g/day of probiotic plus 1% biochar. The basal diet was formulated with a 10:90 forage-to-concentrate ratio to meet nutrient requirements. Water and starter feed were provided ad libitum throughout the experiment. Feed intake was recorded daily, body weight and skeletal growth changes were assessed every two weeks. Blood samples were collected on days 0 (birth time), 35 and 70, and fecal samples were collected to evaluate diet digestibility in the last week of the experiment from all calves. All calves were observed for three days at the end of the experiment to record their feeding behaviors (standing, lying, eating, and ruminating) and non-feeding behaviors (licking, sucking, and chewing on environmental objects). Results: Results indicated that calves that were supplemented with dietary biochar had significantly higher starter feed intake and weaning body weight compared with the non‑biochar groups (P<0.05). Wither height, hip height and abdominal circumference of the calves also increased with biochar supplementation (P<0.05). Concurrent supplementation with probiotic and biochar (treatment 4) further enhanced wither height and hip height (P<0.05). probiotic and biochar supplementation improved apparent digestibility of organic matter and crude protein (P<0.05), respectively, whereas the digestibility of other nutrients was unaffected by experimental treatments. Biochar supplementation also increased blood glucose concentration (P<0.05). Dietary treatments did not significantly affec any of the feeding behaviors. Interaction effects of probiotic and biochar were not significant on any of the parameters measured in this study. Conclusions: Overall, dietary supplementation with biochar, either alone or in combination with probiotic, showed significant positiv effects on performance, skeletal growth indices, and digestibility of nutrients in suckling calves, suggesting that biochar may be used as a functional feed additive to support early-life health and productivity.

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