Greg O'Brien, DEPI Ellinbank
Many dairy farmers are faced with the need to fill significant feed gaps at certain times in the season. The approach taken can have a big effect on milk production, cow condition and profit.
Where purchased feed is required, the general approach is to look for lowest cost feed in terms of cents per megajoule of energy or grams of protein. Sometimes, the lowest cost feed is also low in energy or protein. So diet quality is also important.
When the energy or protein concentration of the diet is down, so to is milk production. Also, the cow compensates by losing cow condition.
Typically, cereal grains are the lowest cost concentrate. Other forms of concentrate such as canola are added to increase the protein content to the level required. It is also important to address the quality of the forage component of the diet (i.e. pasture, silage, hay or crops).
It is not possible to give a recipe for the quality of fodder to buy, as it is possible to use a range of forage qualities if they are balanced in the diet by other high quality feeds. This said, some rules of thumb may be helpful. Look for feeds that are:
- at least 10 megajoules of metabolisable energy (ME) per kilogram dry matter (DM);
- as high as possible in protein (greater than 14 per cent would be good);
- and as low as possible in fibre (under 60 per cent neutral detergent fibre if you can).
This rules out silage and hays made from mature crops with lots of stem.
Hay crops cut at an early stage of maturity and those with lots of leaf compared to stem are best. Legumes tend to be of higher quality than other hays cut at a similar stage of maturity, but you can get good and bad quality in any silage or hay type. Rule out anything with spoilage.
It is common to fill feed gaps with concentrates first, then top up the diet with hay and silage. There is a limit to feeding concentrates. Recent research conducted at DEPI Ellinbank identified that dietary problems can arise when more than 7 kilograms per cow per day of cereal grain concentrates is fed in the bail. The cows were average sized Holstein Friesians, so the limit might be higher for larger cows and lower for smaller cows.
If you are approaching this level of concentrate feeding, be vigilant in looking for signs of diet imbalance. This includes monitoring the milk pickup slips for a significant drop in milk fat test and checking for loose manure (with lots of undigested fibre present and lighter brown in colour than occurs on lush pasture).
The impact of diet quality on milk production was highlighted by Project 3030 research (see table below). In 2005-06, low pasture production required feed to be purchased in the form of hay. Extra concentrates were fed to try and balance up the diet, but the hay that could be sourced at the time was not high quality. Milk production for the season was 520 kilograms milk solids per cow which was the lowest for the three years of the trial.
In the 2006-07 season, despite a severe drought, milk production increased with less use of grain and improvements in forage quality. Also, cow live weight and body condition increased.
The 2007-08 year was good for pasture growth and home made silage was of excellent quality (~11ME). This allowed further improvements in milk production and also highlighted the value of starting the lactation with cows in good condition (~ body condition score 5), as the extra dry matter intake went into milk rather than being split between milk and condition.
Mining body condition may help with cash flow but will be at the expense of milk production in the next lactation or two (not to mention the impact on reproduction).
The bottom line:
- Quality of silage and hay will have a big impact on both milk production and cow condition. If purchasing in hay or silage, do your best to provide your herd with good quality feeds.
- Concentrates can improve diet quality but there is a limit to what can be fed.
- Feeding to maintain cow condition is preferable to mining condition (if cash flow allows).
- Consider selling cull cows early if it is not possible to feed the herd well enough.
The research quoted in this article was supported by Dairy Australia and the Department of Environment and Primary Industries, Victoria. For further information please contact Greg O'Brien, telephone (03) 5624 2288.
|Milk Production (fat + protein kg/cow)||520||568||600|