Feeding for best performance revolves around better understanding a cow’s nutritional demands, and how feed is broken down and used in the digestion system. Feeding for more defined targets such as metabolizable protein (MP) and dynamic net energy (DyNE), amino acid (AA) requirements and understanding the exact energy available from forages and NDF fractions will maximise performance, benefiting cow health, farm business finance and the wider environment.
Making good quality forages is fundamental to feeding for best performance. It is then important understanding how these forages are digested in the rumen, particularly regarding NDF. This will then determine the correct raw materials to balance the ration with to meet cow requirements for optimum performance, health and financial return.
Home-grown forage makes the backbone of any diet and will be the most economical way to feed your cows. Poor quality silages will increase reliance on purchased feeds and decrease margins.
Getting silages regularly analysed is crucial to maximizing herd performance. Regular forage samples will allow for more precise feeding and timely adjustments to be made regarding the dry matter (DM) of forages, minimising imbalances in the ration or overfeeding raw materials.
Rations need to be targeted at the type of cow you have and what you are trying to achieve within the limitations of your system. For example, if lying times are insufficient due to poor cow comfort, diet changes alone will have a limited aff ect on milk yield compared to improving cow comfort and shed design.
Stage of lactation and accurate body weight are going give the parameters to work to and will give a more precise understanding of dry matter intake (DMI). Capturing this information is vital in modeming the cow’s energy partitioning and nutritional demands. Feeding for best performance is then more targeted to the cows that have the potential to achieve high yields. 
More accurate dietary modelling will increase feed efficiency and allow you to better meet the cows’ requirements (Linn, 2012).
Dry Matter Intakes will determine energy balance, influencing lactation performance in terms of production and fertility.
The amount of NDF in the diet will be a limiting factor in terms of DMI. A cow can consume between 1.2 -1.4 % of her BW in NDF e.g. 640 kg cow would be able to consume up to 7680g (Hibma, 2015). Understanding the different fractions of NDF within the forages and raw materials fed to cows will influence how efficiently cows can be fed. This is especially important in early lactation when intakes are deficient compared to energy demands. The quality of NDF in the diet will determine how much energy can be gained from fibre and the percentage NFC (non-fibre carbohydrates) that can be fed to increase energy density while maintaining healthy rumen conditions. Better understanding of the fast, slow and indigestible fractions of fibre in different forages and how these can be matched will allow diets to be better balanced for optimal performance.
Because of the economic value of feeding more homegrown forage, it is important we accurately know how much energy we can expect from forages, how much a cow is physically able to eat, and how quickly it will be broken down and the effect this will have on the rumen. Fibre is broken down into three groups:
Fast Pool – digested within less than 30hrs
Slow Pool – digested within 30 – 240hrs
Undigestible – the material that remains after 240hrs that can’t be digested and used as energy. Energy content of the fibre is calculated backward from what proportion of the fibre remains undigested after 240hrs (Jones, 2016)
If fibre as well as amino acids can be more precisely used within a diet and better understood, milk output per cow and herd margins can be improved.
Current thinking on AA balancing in transition cows is that getting the concentration of lysine and methionine correct in the diet will have more of a direct influence over cell function, improved immunity and reproduction, rather than just milk production alone (French, 2018). 
Feeding the correct concentrations of protected amino acids lysine and methionine pre, and for the first three to four weeks post calving, has been associated with the potential to reduce metabolic issues (Seymour, 2016). It is recommended that the energy contribution from body weight loss be factored in when feeding protected AAs to fresh cows as this will be more precise (French, 2018).
40-60 kg of body fat and 25 kg of lean protein tissue can be metabolized by the cow 6 weeks post calving to cope with the period of negative energy balance (Seymour, 2016).
Amino acids will be mobilized for energy post calving, as well, and maybe more so, than for supporting milk protein synthesis (Schwab, 2018). Intakes and levels of propionate are not able to keep up with energy demand. The increase in mobilization of body tissue places great oxidative stress on the liver. Methionine and its association as a methyl donor can help increase very low-density lipoprotein (VLDL) levels removing more fat from the liver. Helping to reduce the risk of ketosis and maintain intakes. Feeding a high performing dairy cow more precisely is going to have an economic return as it will help drive performance more accurately, reducing wastage and ensuring energy requirements are met without compromising health.
However, environmental factors are then going to severely affect how well she can utilize the feed available. Mixing procedures, building design and stocking density are further going to influence the time budget of the cow and her DMI. Using software such as DairyCOMP can be used to run reports to assess the performance of your herd and identify areas of improvement. Using this data will help make management decisions that can justify financial investment and returns.
Alasdair Taylor
Dairy Specialist
m: 07766 302124
