Motshabi Chadyiwa, Agricultural Research Council-Animal Production
An effective way to reduce the carbon footprint is to reduce animal numbers and increase the production per animal unit. Increased productivity generates less greenhouse gas (GHG) emissions per unit of product. The aim in any breeding programme should thus be to improve production efficiency and revenue and not merely genetic change or higher production. Selection for many of the traditional traits may increase production, but not necessarily productivity or efficiency of production.
The cow-calf production cycle is responsible for most of the energy consumed. In beef cattle, the parent-offspring production cycle is responsible for approximately 72% of the energy consumed from conception to slaughter. In the mature cow, the maintenance requirements represent 70% of her feed expenses and the average feed cost per cow is 42% of the total annual production cost. These values demonstrate why improved cow efficiency is so important.
The three component traits that influence cow efficiency are (1) weaning weight of the calf, (2) feed requirements of the cow to produce the calf and (3) the frequency at which a calf is produced. Whereas, weaning weight and fertility of extensive kept beef cattle can be measured, it is not possible to measure feed requirements directly. However, the principle of a Large Stock Unit (LSU) can be used to estimate the feed requirements of cows. Likewise the weaning percentage can be derived from the inter-calving period.
The formula to estimate cow efficiency is thus:
Cow efficiency = (weaning weight of the calf/ LSU) x weaning percentage
Example: A medium frame cow of 450kg weans a calf of 210kg and has an inter-calving period of 420 days.
Cow efficiency = (210kg / 1.4 LSU) x 0.85 = 127.5 kg calf weaned per Large Stock Unit mated.
If the carrying capacity of the farm is available the cow efficiency can be converted to kg calf weaned per hectare. If the carrying capacity is 6 ha/LSU then the cow efficiency 21.25 kg calf weaned per ha.
In the case of the Afrikaner breed, the cow efficiency increase by 18% over a period of 25 years, which resulted in a decrease of 12% in the carbon footprint.
The challenge is to define breeding objectives that will improve cow efficiency and not just increase production. A possible breeding objective is kg of calf weaned per Large Stock Unit mated. However, a ratio has challenges. It is thus proposed to evaluate the total contribution of the following on the “methane budget/balance” of the cow-calf production system; longevity of a cow, fertility (number of calves born over a lifetime), size of her calves, feed efficiency and maintenance cost of the cow. This can then be combined in a selection index for a cow-calf “methane budget/balance”.
Red Meat Research and Development South Africa (RMRD SA) is funding this research.