DAIRY COW TRANSITION CHALLENGES THE RUMEN MICROBIOTA: NEW INSIGHTS
FROM METAGENOMICS STUDIES In 2018, breakthrough research was published in the Journal of Dairy Science, detailing the effects of the calving transition on the rumen epithelium. This study has been supplemented with metagenomics data, confirming the association between changes in the rumen microbiota and feed efficiency improvements around calving, as well as the protective role of Saccharomyces cerevisiae CNCM I-1077 to help the cows face this challenging period.
The Trial
The transition period in dairy cows spans three weeks pre-calving to three or four weeks post calving. It represents a critical time for the cow with major dietary, metabolic and physiological changes. In particular, the transition from a high-fiber diet to a diet high in rapidly fermentable carbohydrates represents important challenges for rumen health. It can also have a negative impact on the cow’s inflammatory status. A trial was conducted in partnership with Professor Alex Bach’s team (IRTA, Spain) at the Blanca Experimental Farm (Spain), on the impact of transition challenges on rumen health and microbiota profiles as well as the effect of live yeast.
The trial was conducted on 21 Holstein dairy cows from 21 days before calving until 21 days after calving. The diet changed from
28% concentrate before calving (51.2% neutral detergent fiber, NDF, 13.2% crude protein, CP) to 64% concentrate after calving (34.8% NDF, 15.2% CP).
Understanding Metagenomics Data Metagenomics is the genetic identification of the whole microbiota of a host and their relative abundance. These technologies generate millions of genetic sequences. Thanks to biostatistics analysis, this data could be pooled together according to bacteria genus — which shows more than a hundred of different bacteria types (Figure 1). Such analysis can help microbiologists have a better understanding of the complex composition of the microbiota, like that found in the rumen. In the case of transition cows, the goal was to focus on the relative abundance of functionally relevant bacteria. Results from two main categories of microbes were combined: bacteria that degrade complex carbohydrates, such as fiber; and bacteria that degrade rapidly fermentable carbohydrates, like starch.
The data shows that:
• Before calving, the relative proportion of the fiber-degrading bacteria is higher than the ones thriving on rapidly fermentable carbohydrates.
• Post-calving, there is a rapid shift towards a higher proportion of bacteria degrading rapidly fermentable carbohydrates
Protective role of live yeast
The first part of the study published in 20182 showed that feeding S. cerevisiae CNCM I-1077 from three weeks pre-calving positively
Figure 1: Relative abundance of the genera detected in the rumen of dairy cattle as influenced by time relative to calving by operational taxonomic units
improved the rumen dynamics by: Reinforcing rumen epithelium integrity, thanks to higher tight junction gene expression before the challenge.
Increasing resistance to a LPS challenge leading to a lower inflammation after calving The metagenomics data further indicate the protective role for the live yeast:
• Before calving, the relative proportion of fiber-degrading populations is significantly higher (P<0.05).
• Post-calving, the live yeast group showed higher dry matter intake, leading to a 1.21 kg/day increase in non-fiber carbohydrates. This would have negatively impacted rumen pH and microbial balance leading to a higher proportion of rapidly carbohydrate degraders. Instead, there was no statistical difference with the control group that consumed less fermentable carbohydrates.
Dr. Bach explains: “Because LEVUCELL SC cows consumed more feed, a lower rumen pH and greater relative abundance of Prevotella (rapidly fermentable carbohydrate degrader) would have been expected, unless LEVUCELL SC had exerted a positive effect on rumen pH.”
SFT NEXTGEN CONFERENCE THE FARM ANIMAL NUTRITIONIST – INTO THE 2020S.
The SFT NextGen Conference: The Farm Animal Nutritionist – into the 2020s, will take place on Wednesday19th February 2020 at The Windmill Village Hotel, Birmingham Road, Allesley, Coventry CV5 9AL. NextGen is an investment by the SFT to address the needs and interests of those who are:
• Considering careers in the animal feed industry e.g. Undergraduate and Postgraduate students, Careers Advisers etc
• In their early career years in the agricultural livestock or feed industry.
• Established in the farm livestock feed industry but seeking a broader and deeper knowledge.
This is the 3rd in the series of SFT NextGen conferences dealing, in an informal format, with the fundamentals of a range of issues which are relevant to animal nutritionists.
The seminar fee is £50.00 plus VAT to include the seminar, light refreshments and lunch. A discounted fee of just £15.00 (including VAT) is available to students who are registered in full time education. Complete your registration and payment online through the SFT website.
FEED COMPOUNDER JANUARY/FEBRUARY 2020 PAGE 53
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