Ensuring an optimal weaning transition: Activate gut immunity and positively influence rumen microbiota to benefit calf performance

The weaning transition is a major challenge in calf management. With a proper plan for nutrition (milk and solid feed), producers can help support calves at this critical period to safeguard future performance, health and longevity.

Marine Gauthier
Ruminant Technical Development Manager
Lallemand Animal Nutrition

Calf management is crucial and will influence the performance of the the adult cow. Replacement costs can be critical to determining profit or loss on dairy farms. One way to reduce this cost is lowering the age at first calving.

Actions that contribute to the reproductive performance of heifers can improve the financial position of the farm overall. In addition, supporting greater milk production during the first lactation helps investments in heifers reach economic equilibrium earlier. Research (Abuelo et al. 2021) shows heifers affected by diarrhea as calves showed lower average daily gain at weaning and a lower first lactation performance with -325 kg of milk when looking at the 305 day mature equivalent (ME) milk production standardized value. In addition, heifers diagnosed with diarrhea and bovine respiratory disease (BRD) rend to have increased difficulty at insemination and during calving.

The weaning transition is a major challenge in calf management. With a proper plan for nutrition (milk and solid feed), producers can help support calves at this critical period to safeguard future performance, health and longevity.

“Research has shown a positive correlation between the number of bacterial strains in the rumen and the length of rumen papillae, as well as the thickness of the rumen wall and weight of the rumen, all linked to optimal rumen function and efficiency.”

This is the period when the digestive tract of calves undergoes significant and extensive changes as it evolves from its initial monogastric function towards a ruminant function. During the first days of life, milk is the single dietary compound of the baby calf diet. The baby calf reticulo-rumen is bypassed. The rumen starts from a volume of 0.5L to 4L at 4 months of age and will grow drastically to 100-150L in the adult cow. In addition, the rumen papillae will develop with the rumen. Knowing that the papillae surface represents the rumen nutrient absorption surface, it is important to take care of its development for an optimal nutrient absorption in the adult cow. Rumen papillae development is strongly linked to the diet and rumen microbiota of calves during the first month of life (Chaucheyras-Durand et. al, 2001). Feeding solid grain will nurture the microbiota that will produce propionic acid and butyric acid. These two volatile fatty acids (VFAs) will stimulate papillae development.

In a nutshell, there are two parameters to ensure proper rumen function development: a beneficial microbiota and a beneficial diet to allow these microbiota to thrive.

Practical tips: How to assess proper rumen development on the farm
– Calf starter intake is an important indicator. The target for early weaned calves (~6 weeks) is 0.9-1.4 kg of starter grain per head per day for 3 consecutive days before weaning. This goes up to 1.8-2.3 kg/head/day for calves weaned at 8 weeks (DCHA, 2016).

In U.S. dairy calf operations, economic consequences of long-term diarrhea outbreaks are estimated to be around 71.15$ per calf (USDA, 2014).

During early life, while immunity is still weak, calves experience a lot of external stressors (transportation, transition from liquid to solid feed, dehorning, etc.).All these stressors increase the risk of morbidity and mortality by making the immune system more vulnerable. This can lead to visible signs of poor immune defences such as digestive and respiratory diseases. The major causes of mortality and morbidity are digestive challenges (32% and 51%, respectively) (Urie et al., 2018).

Figure 1. Pre- and post-weaning major rumen bacterial populations (Adapted from Meale et al., 2016).

In addition, weaning is a challenge for the animal, the rumen and its microbiota. Ruminal diversity decreases due to increased starter intake and decreased rumen pH. The microbial composition changes dramatically at weaning (Figure 1).

First, the objective will be to strengthen gut immunity to secure the fragile digestive system and limit diarrhea and respiratory diseases. The gut plays an important role in the immune defense system as innate and acquired immunity are concentrated within the gastrointestinal lymphoid tissue (GALT). GALT gathers up to 70% of the body’s white blood cells. Using nutritional additives to support a balanced immune response can be a winning strategy to improve calf health and performance around weaning.

In this context, a new generation feed ingredient, YANG — which includes specifically selected yeast fractions — has been proven to help maintain the health of calves and other young ruminants.

YANG is a multi-strain yeast derivative formulated to strengthen animals’ natural defenses with a patented, synergistic effect on the immune response. It combines two complementary actions that reinforce animals’ natural defenses:
– A strong pathogen binding capacity, effective against a wide range of undesirable bacteria compared to single-strain yeast derivatives.
– A patented broad and balanced immune modulation that doesn’t carry the risk of over-stimulation sometimes observed in cases of single immune receptor activation by traditional yeast derivatives.

Figure 2. Multi-studies synthesis, percentages of calves treated at least once with antibiotics during the trial. BW = body weight, d = day, ST = YANG included in the starter feed, MR = YANG included in the milk replacer.

Studies (Figure 2) were conducted on different feeding conditions with calves during the pre- to post-weaning period. Results show calves fed YANG in the starter feed (ST) or milk replacer (MR) exhibit a significant reduction in the percentage of calves treated with antibiotics. These results suggest that YANG activates immunity and allows calves to better cope with digestive sensitivity at this critical period of life.
Second, the objective during this period is to support rumen microbiota and papillae development, which helps ensure a well-prepared rumen through the weaning transition.

Probiotic yeasts, also called live yeast, have the ability to interact with rumen microorganisms and can enhance rumen function and microflora establishment. The rumen-specific live yeast Saccharomyces cerevisiae CNCM I-1077 (LEVUCELL SC) is a particular yeast strain that has been selected from among thousands of different strains by INRA scientists for its ability to improve rumen function. In calves, various trials confirmed its benefits on rumen maturation, feeding behavior and growth performance.

When fed S. cerevisiae CNCM I-1077, young ruminants have shown an accelerated rate of establishment of two major microbiota populations for fiber degradation: the cellulolytic bacteria and ciliate protozoa (Chaucheyras-Durand and Fonty, 2002). In addition, rumen wall papillae development is improved with longer papillae (P=0.06) (Figure 3) (Bittar and Ferreria, 2007). As a result, the rumen absorption surface is increased, which favors nutrient uptake and contributes to better performance.

Figure 3. Effect of S. cerevisiae CNCM I-1077 on rumen papillae development (Bittar and Ferreria, 2007).

The results of this improved rumen development can be seen with an increase in starter intake when calves are fed the live yeast. Multiple trials conducted with various feeding systems consistently indicate the positive effect of S. cerevisiae CNCM I-1077 supplementation on starter feed intake (Figure 4) from pre-weaning to post-weaning when included during the weaning transition phase: +20% on average.

Figure 4. Starter intake optimization thanks to LEVUCELL SC supplementation

In calves, the first months of life are critical for future production. Nutrition management is key to limiting the impact of early stresses on the digestive system and ensuring optimal rumen development. In addition to good management practices, producers can include beneficial nutritional tools to help maintain calf health, support starter intake and reinforce rumen papillae development for optimal adult performance. Well-researched tools include probiotic live yeast such as LEVUCELL SC, and innovative yeast fractions such as YANG.

How to supplement live yeast for a smooth weaning transition in practice
S. cerevisiae CNCM I-1077 (LEVUCELL SC) can be supplemented to calves from birth in the solid feed.

1. Abuelo A., C. Faith, A. Hanes, J. L. Brester. 2021. Impact of 2 Versus 1 Colostrum Meals on Failure of Transfer of Passive Immunity, Pre-Weaning Morbidity and Mortality, and Performance of Dairy Calves in a Large Dairy Herd Animals11(3), 782.
2. Bach A. and Ahedo J. 2008. Record Keeping and Economics of Dairy Heifers. Vet Clin Food Anim 24: 117–138
3. Bittar C.M. and Ferreria L. 2007. Avaliação da suplementação com culturas de levedura (Saccharomyces cerevisae) para bezerros leiteiros: crescimento do trato digestório e desenvolvimento do rúmen . Annual Meeting of the Brazilian Society of Animal Science (poster)
4. Chaucheyras-Durand F. and G. Fonty. 2001. Establishment of cellulolytic bacteria and development of fermentative activities in the rumen of gnotobiotically-reared lambs receiving the microbial additive Saccharomyces cerevisiae CNCM I-1077. Reprod. Nutr. Dev. 41: 57-68
5. Chaucheyras-Durand F. and G. Fonty. 2002. Influence of a probiotic yeast (Saccharomyces cerevisiae CNCM I-1077) on microbial colonization and fermentations in the rumen of newborn lambs. Microb. Ecol. Health Dis. 14:30-36.
6. Dairy Calf and Heifer Association (DCHA) Gold Standards, Second edition (2016)
7. Urie N.J., E. Lombard, C.B. Shivley, C.A. Kopral, A.E. Adams, T.J. Earleywine, J.D. Olson, F.B. Garry. 2018. Preweaned heifer management on US dairy operations: Part V. Factors associated with morbidity and mortality in preweaned dairy heifer calves. Journal of Dairy Science 101(10):9229-9244.

About Marine Gauthier
Marine Gauthier own a Master’s degree (Engineer) in Animal Production from the National Agronomy University of Toulouse (ENSAT, France). After working for Lallemand R&D within the IRTA research institute in Barcelona (Spain), she is in charge of ruminant technical development support by coordinating commercial and scientific trials for new applications in calves, beef and small ruminants at Lallemand.