# Differential effects of 3-nitrooxypropanol supplementation on milk fatty acid profiles in 3 different dairy breeds

## TL;DR

This study shows that adding 3-NOP to dairy cow feed changes milk fatty acids differently depending on the cow breed.

## Contribution

The study reveals breed-specific effects of 3-NOP on milk fatty acid profiles, highlighting differences in de novo fatty acid synthesis among dairy breeds.

## Key findings

- 3-NOP significantly increased short-chain fatty acids in milk from Danish Holstein cows.
- Danish Red cows showed no significant changes in milk fatty acid composition with 3-NOP supplementation.
- Breed differences in milk fatty acid profiles may be due to variations in de novo fatty acid synthesis.

## Abstract

Summary: 3-Nitrooxypropanol (3-NOP) is a synthetic compound used to reduce methane emissions from dairy cows. Its effect on cow performance and milk composition has gained increasing interest in recent research studies. In the present study, the effect of 3-NOP on milk fatty acids (FA) was investigated in 3 different dairy breeds, namely Danish Holstein (DH), Danish Jersey (DJ), and Danish Red (DR). The results showed that feeding 3-NOP significantly increased the concentration of short-chain FA in the milk of DH cows to a greater extent than in DJ cows, whereas no significant changes were observed in DR cows. In conclusion, the results indicated that the effect of 3-NOP on milk FA composition is breed specific, likely due to inherent differences in de novo FA synthesis among breeds.

Summary: 3-Nitrooxypropanol (3-NOP) is a synthetic compound used to reduce methane emissions from dairy cows. Its effect on cow performance and milk composition has gained increasing interest in recent research studies. In the present study, the effect of 3-NOP on milk fatty acids (FA) was investigated in 3 different dairy breeds, namely Danish Holstein (DH), Danish Jersey (DJ), and Danish Red (DR). The results showed that feeding 3-NOP significantly increased the concentration of short-chain FA in the milk of DH cows to a greater extent than in DJ cows, whereas no significant changes were observed in DR cows. In conclusion, the results indicated that the effect of 3-NOP on milk FA composition is breed specific, likely due to inherent differences in de novo FA synthesis among breeds.

•3-NOP increases short-chain fatty acids in milk from DH cows by 9.18%.•3-NOP increases short-chain fatty acids in milk from DJ cows by 4.13%.•3-NOP increases short-chain fatty acids in milk from DR cows by 2.66%.•The effect of supplementing 3-NOP on milk FA composition is breed specific.

3-NOP increases short-chain fatty acids in milk from DH cows by 9.18%.

3-NOP increases short-chain fatty acids in milk from DJ cows by 4.13%.

3-NOP increases short-chain fatty acids in milk from DR cows by 2.66%.

The effect of supplementing 3-NOP on milk FA composition is breed specific.

3-Nitrooxypropanol (3-NOP) is a promising and approved antimethanogenic feed additive in dairy farming. The objective of this study was to evaluate breed-specific variation in milk fatty acids (FA) following 3-NOP supplementation. Milk FA composition was analyzed from 3 studies using Danish Holstein (DH), Danish Jersey (DJ), and Danish Red (DR) dairy cows respectively, fed control or 3-NOP supplemented diets. The 3-NOP was supplemented at a dose of 60 mg/kg feed DM. Bulk milk samples were analyzed for milk FA by GC flame ionization detection. The 3-NOP supplemented diets increased the proportion of short-chain fatty acids (SCFA) and decreased the proportion of C16:0 in the milk of DH cows. A similar tendency in milk FA composition induced by 3-NOP was observed in DJ cows; however, the extent of these changes was less pronounced, and no changes were observed in milk FA from DR cows. Indirect comparison among the breeds showed a higher proportion of SCFA in milk from DJ cows, a higher proportion of medium-chain FA in DR cows and a higher proportion of long-chain FA in DH cows. The effect of 3-NOP on milk FA composition appears to vary between breeds; however, this variation may also be influenced by differences in feeding regimens between breeds, making further studies worthwhile to better understand these interactions.