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Biotin and milk production

Most research into biotin supplementation in dairy cows has concentrated on hoof health, where the importance of this B vitamin has long been recognized. However, a growing body of work is also reporting significant increases in milk production and component yields in biotin-supplemented cows when compared with unsupplemented herdmates.

The studies suggest that unsupplemented dairy cows may have marginal deficiencies or inadequacies of this essential nutrient, especially when the animals are fed the high-concentrate diets typical on today's dairy farms.

Most recently, researchers at The Ohio State University (Zimmerly and Weiss, 2001) assessed biotin fortification and milk production using typical diets for high-producing cows. Treatments were 0, 10 and 20 mg of supplemental biotin per head daily, included in rations that were 70 percent forage during the late dry period and 50 percent forage during lactation. The study lasted from approximately 14 days prepartum through the first 100 days of lactation

Milk production increased linearly (P < 0.05) with biotin supplementation (Figure 1), although dry matter intake did not differ by treatment. Protein yield also increased linearly (P < 0.02) with biotin supplementation. Cows receiving 20 mg per day had average daily milk production of 87.3 lbs (39.7 kg), compared with 81.2 lbs (36.9 kg) from the unsupplemented controls. This represented a 6.1 lb increase in milk production over unsupplemented controls. Cows receiving 10 mg of supplemental biotin per head daily had intermediate milk production of 83.2 lbs (37.8 kg) per day, or 2.0 lbs more than the controls.

 
Figure 1

The authors noted that because of the immediate increase in milk production with biotin supplementation, the response was almost certainly due to metabolic changes rather than improved hoof health. Indeed, biotin is an essential coenzyme in carbohydrate, fat and protein metabolism. In the cow, biotin is a required cofactor in the enzymatic pathways for ruminal synthesis of propionic acid, as well as hepatic gluconeogenesis from propionic acid, and for fatty acid synthesis. It is also involved in conversion of carbohydrate to protein and protein to carbohydrate, and also in the conversion of protein and carbohydrate to fat.

Yet cows receiving typical modern dairy rations may have a marginal biotin status for two reasons. First, unfortified rations provide an uncertain dietary source. While many feedstuffs contain biotin, scientists do not know how much of the vitamin in feed components is actually available to meet the cow's needs. There have been few bioavailability studies with any species, but poultry researchers reported that less than half of the microbiologically determined biotin in feedstuffs is biologically available. It is also known that only d-biotin is biologically active.

Second, diet can affect ruminal synthesis of biotin, which would otherwise provide cattle an advantage over monogastric species in biotin supply. When rations include high proportions of readily fermentable sugars and starch, the resulting acidic conditions cause imbalances among ruminal microbial species. Abel and Gomez (1997) first reported that reduced forage:grain ratio reduced rumen microbial synthesis of biotin.

Similarly, Da Costa Gomez et al. (1998) reported that a reduction in the dietary ratio of forage to grain significantly reduced ruminal synthesis of biotin. As dietary forage content fell from 83 percent to 17 percent, there was a linear decrease in biotin synthesis in rumen continuous culture (Figure 2). With the forage:grain ratio at 50:50, biotin synthesis in the rumen was only half of what it had been with a forage-to-grain ratio of 83:17.

 
Figure 2

In the recent Ohio work, Zimmerly and Weiss (2001) reported that average plasma and milk biotin concentrations increased linearly (P < 0.01) as biotin fortification increased. Average plasma biotin concentrations were 0.67, 1.20 and 2.05 ng/ml for animals in the control, 10 and 20 mg treatments, respectively, while milk biotin averaged 22.6, 31.3 and 69.8 ng/ml. This indicates that supplemental biotin is well absorbed when fed to dairy cows.

Like the Ohio researchers, other scientists have recently reported significant increases in milk production, milk components or other measures of dairy cow productivity with biotin supplementation. In work at Washington State University, for example, Bergsten et al. (1999) analyzed 305-day milk yield in 98 high-producing dairy cows fed either 0 or 20 mg per day of supplemental biotin via computer feeder. The rolling herd average was 22,021 lbs (10,010 kg) per cow, or 72.2 lbs (32.2 kg) per day.

Data were adjusted for parity, days in milk and previous lactation milk yield. Cows fed supplemental biotin produced 1,932 lbs (877 kg) more milk over 305 days, or 6.3 lbs per day. This closely matches the milk response of 6.1 lbs/day observed by Zimmerly and Weiss in the Ohio study. There were also significant reductions in sole hemorrhage and hoof wall ridging in the biotin-supplemented cows, even though hoof health was generally good at the outset of the study.

Midla et al. (1998) also reported significantly increased milk production in first-lactation heifers receiving 20 mg per head daily of biotin compared to unsupplemented controls. Supplemented animals produced 693 lbs (314 kg) more milk over the entire 305-day lactation, or 2.7 percent more than control animals. The improved milk production was accompanied by a significant reduction in the incidence of white line separation.

In a study during the first five months of lactation, Bonomi et al. (1996) reported that cows receiving 10 mg of biotin per head daily produced 2 kg (4.4 lbs), or 4.7 percent, more milk per day than unsupplemented controls. Milk fat and milk protein levels were also increased. The increase in milk protein levels was significant for months three to five, while the other measures of production were significantly increased for all five months of the study. These authors also reported that supplemental biotin increased blood glucose concentration and milk component yields. The milk increase was observed during the first month of supplementation, which began at calving.

According to Bonomi et al. (1996), these results were consistent with the metabolic function of biotin as a cofactor in gluconeogenesis and fatty acid synthesis. They suggest that the biotin status of higher-producing cows appears to be inadequate as judged by the immediate increase in milk yield observed in the study.

Other work has shown significant improvements in milk income with supplemental biotin for other reasons. In Australian work, Fitzgerald et al. (2000) reported reduced somatic cell counts in supplemented dairy cows compared to unsupplemented controls. In addition, because there was less lameness in the biotin-supplemented cows, there were fewer antibiotic treatments and less milk discard.

Because microbial synthesis of biotin occurs in the intestinal tract of most species, it is difficult to determine minimum requirements for practical diets. More important than the minimum requirement is the optimal level of biotin supplementation of livestock diets that will produce the greatest overall economic return.

Based on these studies and those involving hoof health, lactating cows should receive 20 mg biotin per head daily throughout lactation and 10 to 20 mg per head daily during the dry period.

 

References:

  • Abel, H., and C. Gomez. 1997. Unpublished data. Inst. Agri. Nutr., Gottingen, Germany.
  • Bergsten, C., et al. 1999. A controlled field trial of the effects of biotin supplementation on milk production and hoof lesions. J Dairy Sci. 82 (Suppl. 1):34.
  • Bonomi, A., et al. 1996. Dairy cattle ration integration with rumen-protected biotin. Effects on production and reproductive efficiency. La Revista di Scienza dell¹Alimenta. 25:49.
  • Da Costa Gomez, C., et al. 1998. Effect of varying hay/barley proportions on microbial biotin metabolism in the rumen simulating fermenter RUSITEC. Proc. Soc. Nutr. Physiol. 7(abstr.).
  • Fitzgerald, T., et al. 2000. The influence of long-term supplementation with biotin on the prevention of lameness in pasture-fed dairy cows. J. Dairy Sci. 83:338.
  • Midla, L.T., et al. 1998. Supplemental dietary biotin for prevention of lesions associated with aseptic subclinical laminitis in first-lactation Holsteins. Am. J. Vet. Res. 59:733-738.
  • Zimmerly, C.A., and W.P. Weiss. 2001. Effects of supplemental biotin on performance of Holstein cows in early lactation. J. Dairy Sci. 84: 498-506.

 
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