More than just fat

Dietary fats are an essential element in dairy cow nutrition. Traditionally, fats have been fed to increase the dietary energy, due to their high energy concentration; around 2.25 times higher than other nutrients.

More than just fatNot only do they have a high energy concentration but can also help to improve body condition, milk production and reproduction. Fats are a form of triglyceride, made when three fatty acid (FA)
molecules react with a glycerol molecule. The fats characteristics can be related to the properties of the fatty acids, each having an individual profile and producing different responses from the cow. A basic forage diet generally contains around 3% fat, however, when milk production is high dietary energy demand increases. High yielding cows require closer to 6% fat in their diet, especially during the early stages of lactation.

 

Whilst fat demands increase, the rumen cannot cope with much higher than 3.5% fat unsaturated fat in the rumen. This is due to the fact that the fat in most feed ingredients causes an oil slick in the rumen. Some FA’s can also be toxic to the beneficial rumen bacteria, reducing fibre digestion and causing a decline in rumen health. To combat this, FA’s are also available in rumen protected form, bypassing the rumen without affecting fermentation and allowing energy intake to be increased. This is where the feeding of rumen protected fat supplements can be of great benefit.

When feeding supplementary FA, it is important to consider both the stage of lactation and what you aim to achieve through its inclusion. Differing FA’s are of most benefit at various lactation stages and at different ratios.
During early lactation, the cow is likely to be in negative energy  balance (NEB), due to reaching her peak yield (at approx. 6-8 weeks), but not peak dry matter intake (DMI). This means that
she will be losing body condition as her body converts fat to energy to combat NEB. At this stage, the best FA supplements for inclusion are that of C16:0 and C18:1 at a ratio of 60:30. The addition of C18:1 promotes the partitioning of nutrients towards body reserves and improves feed efficiency, thus reducing the effects of NEB through increasing energy intake and improving
fertility. The remaining 10% of dietary fats during this period should be made up by other FA’s, such as C18:3 to help further improve fertility through influencing reproductive hormones and improving embryo survival.
In mid to late lactation phases, the ratio of C16:0 can be taken up to 80-90% to increase the partitioning of nutrients towards milk fat production. Some mid/late lactation supplements continue
to include small amounts of C18:1 to help improve or maintain milk yield. However, intake should be limited to prevent cows becoming overly fat in late lactation and ahead of the important transition phase. For those calving all year round, and using just one TMR throughout, a blanket inclusion of C16:1 and C18:1 supplements at a 70:20 ratio should be considered.

Supamet MP and Dynamet MP contain a blend of fatty acids at the required ratios to meet the differing requirements of early and mid-lactation

As part of the AminoMatch nutritional approach two new supplementary fat products join the range. Supamet MP and Dynamet MP contain a blend of fatty acids at the required ratios
to meet the differing requirements of early and mid-lactation without suppressing dry matter intakes. Both of these fats contain a supplementary source of rumen available methionine
and bypass methionine, which has been shown to be effective at manipulating butterfat levels. Fats are an essential part of the AminoMatch nutritional approach when the milk potential from
energy falls below the potential yield from metabolizable protein (MP) supplementary fat will ensure optimum performance. In conclusion, whilst supplementary fats can be of great
benefit to the cow, it is vital to consider the profile of the FA  and the stage of the cow’s lactation cycle. By tailoring your FA selection and inclusion ratio, the greatest positive results can be
achieved. Although FA’s have many positive influences on the cow’s yield and health, it is critical to look at their interactions and effect on DMI, digestibility, rumen health, milk composition, body condition and fertility.

Rachel Gardner
Dairy Technical Specialist (Trainee)
m: 07810 444834
e: rachel.gardner@wynnstay.co.uk

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