Dairy R&D items


Date: 2 February 2024
Discipline: Environment

Feed efficiency is highly correlated with economic sustainability on a dairy farm. Cows with higher feed-use efficiency are usually characterized by a higher feed intake per unit live weight, have lower maintenance requirements, partition more metabolizable energy to milk than body tissue, and lose less energy in waste and body weight. Further factors to bear in mind when considering economic sustainability are, (1) cows’ weight loss during the high production phase should be short-term as long-term weight loss may predispose them to metabolic disorders and poor reproductive performance, and (2) milk price is largely determined by milk protein and fat production in South Africa.

On pasture, energy is often limiting due to the composition being higher in fibre than on TMR and therefore cows rarely achieve their production potential. Within such constraints the question becomes important which animals may be more suitable to farm with. In this context then, the authors cited posed the question whether Holsteins or Jerseys are more suitable for pasture-based systems.

In their study, the lactation records of 122 Holstein and 99 Jersey cows varying in lactation numbers 1 to 6 and managed under similar conditions, were collected from 2005 to 2014. Their feed intake and nutrient requirements were calculated from standard equations of the National Research Council and the Cornell Net Carbohydrate and Protein System.

The results for lactation numbers were calculated separately but averaged in the table below, as there was no significant lactation number x parameter interaction.

Comparison between Holstein and Jersey on various parameters affecting efficiency (calculated per kg DMI, unless otherwise indicated)

         Parameter           Holstein            Jersey      Averaged SD
Milk yield, kg              1.36              1.27              0.01
Milk fat, g52.4              58.4              0.35
Milk protein, g              42.7              45.1              0.30
EC milk, kg              1.30              1.36              0.01
DMI/kg BW (%)              3.13              3.51              0.02
Negative EB (days)            102.4              74.2              2.30
Energy reserves (MJ)            -53.9             -39.7                 –
NE/100g milk fat              13.7              12.5              0.10
NE/100g milk prot.              16.7              16.2              0.14
NE/kg EC milk             5.52              5.35              0.04

The Holsteins had higher milk yield per kg DMI, whereas the Jerseys had higher yields in milk fat, milk protein and energy-corrected (EC) milk per kg DMI. The Jersey cows also had higher DMI per kg body weight (BW). During transition and the early lactation stages, the Holstein and Jersey cows were in negative energy balance (EB) with the lowest energy reserves reached at about 23.5 days post-calving – the Jerseys being less affected than the Holsteins. Furthermore, the Jerseys used proportionally less net energy (NE) intake to produce 100g milk fat and protein, and one kg EC milk.

It was concluded that despite the higher milk yield of the Holsteins, the higher milk solid component of the Jerseys – which resulted in higher EC milk per kg DMI resulted in the Jerseys being more production and economic (milk price argument included) efficient. This is corroborated by the more feed-use efficiency and energy balance traits, including the less intense negative energy balance. Overall then, the results suggest that the Jersey breed should be the preferred breed for pasture-based systems in South Africa.