Feeding preweaning Holstein calves a synbiotic supplement increases their energy-corrected milk yield as lactating cows.

A balance between the microorganisms in the gut is known to be essential for optimal health, growth, and production. Any disruption of this balance may lead to gastrointestinal disorders, weak immunity, and increased vulnerability to diseases, and which could have lasting consequences for future milk production. For example, diarrhoea during the pre-weaning period can reduce future milk yield. To prevent such conditions, prebiotics and probiotics such as Saccharomyces cerevisiae yeast culture, Bacillus subtilis, and Lactobacillus plantarum can be supplemented as they enhance the growth of beneficial bacteria in the gut, thereby improving the health and growth of pre-weaning calves.

As mentioned, early-life nutrition and health also influence future milk yield, but little is known about the long-term influence of nutritional additives such as prebiotics and probiotics. Because most studies focus primarily on the short term effects of prebiotic and probiotic additives during the pre-weaning period, there is a gap in our understanding of the potential long-term benefits of these additives on milk production. Therefore, in the study cited, calves were followed to assess the long-term effects of pre-weaning supplementation with pre-, pro-, or synbiotic on future milk yield. This was accomplished by analysing daily milk, protein, and fat yields and monthly energy-corrected milk (ECM) yield from these calves as lactating adult cows.

The study was a retrospective analysis of milk yield records from dairy cows that were randomized at birth to one of four twice-daily treatments administered during the pre-weaning period: (1) control, no additive (CON), (2) prebiotic (PRE; 7 mL of Saccharomyces cerevisiae yeast culture), (3) probiotic (PRO; Bacillus subtilis and Lactobacillus plantarum, delivering ~1 billion and 250 million cfu per head per day, respectively), or (4) symbiotic (SYN; combination of both PRE and PRO at the same dosages as the PRE and PRO treatments). The study involved 1 296 Holstein cows over their first three lactations for a total of 2 735 lactations. Monthly test day records for milk yield, fat, and protein were used to calculate ECM, standardized to 4% fat and 3.3% protein, totalling 26 464 monthly test day milk records.

The results showed that for the first lactation, ECM yield was estimated at 28.7 kg on the first day in milk (DIM), peaked at 42.1 kg, and declined to 21.3 kg by 305 DIM. For lactation 2-3, ECM yield was 41.1 kg at one DIM, peaked at 54.2 kg, and was 33.7 kg at 305 DIM. The SYN treatment increased ECM yield by 1.00 kg/day compared with CON. This increase was primarily due to an increase in milk fat yield, with 0.048 kg/day more fat produced compared with the control group. No differences in ECM yield between PRE, PRO, or CON were observed.

In Summary: The study showed that feeding a combination of Saccharomyces cerevisiae yeast culture, Bacillus subtilis, and Lactobacillus plantarum during the pre-weaning period increased ECM yield (or fat and milk yields) in adult lactating Holstein cows. The increase in ECM yield could be explained by a significantly higher fat content in milk produced by the cows fed the combination supplement during their pre-weaning period, compared with the control cows.