Grain - to feed or not to feed

The inclination to reduce grain inputs this season has been assisted by a favourable winter and spring.  Summer is now starting to take its grip and pasture feed is quickly disappearing and being replaced by silage and crops.  If summer continues to be dry and hot then most of us will be facing a significant feed shortfall in February and March that is normally offset by grain.

Determining the level of grain feeding in the herd that is profitable can be a daunting task.  Some farmers make a rash decision to either feed at high levels regardless of the economics, or to pull out grain all together and let seasonal conditions take control of lactation level.

Whatever the decision, it is valuable to make some assessment of the impact of grain or no grain before acting.  Some of the factors for consideration are discussed below.

Assessing the return in immediate milk production

In summer and autumn, in most situations, an extra kg of grain fed will not substitute for the intake of silage pasture or crop unless the cows are already being provided with more than they can eat.  Therefore their total intake will rise by close to the equivalent of the extra grain provided.

Some of this grain will be channeled into milk production and some to body condition score.  How much goes into condition score will depend on a number of factors.

Stage of lactation.
A fresh cow will lose condition score for the benefit of milk production<p>

Level of production
As production rises cows will reach a point where they will start putting some on their backs rather than extra milk if they are well enough fed<p>

Quality of the diet.
If cows have  poor quality forage or a low protein diet they will be less able to use the high energy levels in the grain to produce milk<p>

Acidosis.
In circumstances where the fibre level is too low in the diet, extra grain will potentially exacerbate an underlying acidosis problem

Genetic merit of the cow.
Some cows will respond more positively to grain with milk rather than body condition score.

There are many trials that demonstrate different responses to grain over varied situations.  There is enough energy in a kg of grain to produce almost 2 litres of milk if all were to be channeled into production, however trials invariably show a lesser response at this time of year.  It is reasonable to assume that a cow being underfed in mid lactation is capable of producing an extra litre.  Fresh cows may respond more than this whilst stale cows may respond less.

Based on a return of 1 litre for 1kg of grain fed, with the price of cereal grains at 30 cents per kg, it will be difficult on milk production alone to see an economic response until milk reaches 30 cents per litre.  This price will be received by most suppliers for a standard 4.2/3.3 test milk at premium quality this autumn once step-ups and productivity incentives are applied.

Body condition score

This season the tendency to reduce grain inputs over spring has resulted in some body condition score loss.  This is probably not of great concern unless herds have been fed no grain for extended periods.  The repercussions are significant both for animal health and reproductive performance and for production the next lactation.<p>

It takes 200-300 kg of extra feed to put on one extra condition score to a cow in late lactation.  If an extra 3kg of grain are fed per day for the last 100 days of lactation then it is likely that cows will dry off one condition score heavier.  The response in the next lactation to an extra condition score is to produce at least 10 kg of extra butterfat at no extra feed cost.  Therefore the value of extra production next year is around $70 per cow.
Over the next 100 days, if we only receive an average of 27 cents per litre and grain remains at 30 cents per kg, then based on feeding an additional 300 kg per head over that period, we will have lost 3 cents per kg fed or 9 cents per day.  This is a $9 loss offset by a gain next lactation of $70.

There are also other factors to consider such as a change in milk and grain price, an early autumn break and the benefits of improved body condition score on reproductive performance and animal health during the next lactation.  The economics of this scenario are even more convincing for fresh cows since there is much more at stake.
Summary

Cows should at least be fed to body condition score in late lactation.  It is not feasible to think that cows can put on condition in the dry period during the last 8 weeks of their gestation.  Unless they are to have a longer dry period, then the ability to more efficiently put on body weight whilst still milking, should be utilised.

Unless there is considerable crop available it is likely that at least 3-5 kg of grain per day will be needed to make up a typical daily intake of 15-18 kg dry matter.  If silage quality and quantity is limited it is possible that additional protein will need to be added to the diet to elicit an adequate response.

Click here to view the rest of the 2002 February newsletter.