Top feed, top cattle

The challenge for beef farmers is to meet animal feed requirements as much as possible from seasonally available pasture, Dr Ken Geenty writes.

The main drivers of beef cattle profit are productivity and efficiency. Numbers and weights of calves weaned per cow mated represent productivity, whereas cow liveweights, progeny growth rates, along with feed consumed, contribute to efficiency. Top pasture and animal management are needed to boost the components of these profit drivers.

The challenge for beef farmers is to meet animal feed requirements as much as possible from seasonally available pasture for desired animal performance and marketing. Not an easy task, as feed demands of calving and progeny growth don’t always match seasonal pasture supply which can vary each year. In fact the most profitable beef production system may not be biologically efficient using only seasonal pasture.

At the start of each season planning and implementation for matching feed supply and demand needs to be at different levels. First, a knowledge of average seasonal pasture growth for your farm is required. Regional pasture growth curves for your area can generally be found from the Farmax pasture growth forecaster or from the Beef + Lamb NZ Q-Graze manual.

Then from discussions with your adviser, or from previous years’ experience, you’ll get a pretty good idea of stock carrying capacity. From this, an estimate of timing of feed surpluses and deficits will allow determination of types and amounts of forage crops and/or feed supplements required.

A few ways to help match feed supply and demand are as follows, with some more costly than others:

• Buying and selling stock at key times
• Manipulating stock performance to match pasture growth
• Conserving feed as supplements to cope with deficits
• Using animal body condition as a buffer
• Buying feed supplements if cost-effective
• Manipulating calving dates and stocking rate
• Saving some paddocks for forage crops
• Strategic use of nitrogen and fertiliser.

The biggest challenges, as shown in Fig. 1, will generally be managing the spring-summer surplus and coping with winter and autumn deficits. In this example, with mixed cattle and sheep, feed supply and demand are matched by conserving and feeding hay.

Alter the calving date

Many hill country farms with no flats won’t be able to make hay. In these cases a very effective way of better matching feed supply and demand is to alter calving date as shown in Figure 2.

Here, October calving matches beef cow feed requirements to Taihape hill country pasture growth averaged over three years. In this example matching of cow feed requirements with pasture production is quite precise meaning cows will be well fed and productive while maintaining pasture quality and minimising waste.

Once strategic planning of stocking rate, calving dates and feed supplementation have been completed, day-to-day feed planning needs to be implemented. Because the key feed ingredient is energy,w the metabolisable energy (ME) system, adopted for farm animals world-wide, will be used. This system is simple and easily applied.

Quantities of ME in most pastures, forage crops and supplements are readily available online and in publications.

Other important dietary components such as protein, fibre, minerals and vitamins are conveniently balanced in high quality pastures and forages, except where there are known mineral deficiencies in the soil eg. selenium, cobalt and copper in some areas of New Zealand.

These can be corrected in fertilisers or administered directly to animals. Many supplementary feeds such as cereal grains are deficient in protein and some minerals and vitamins which also need to be added. This information is normally available with the published feeding tables.

A good place to start finding cattle feeding information is the Beef + Lamb NZ website beeflambnz.com where the publication ‘Guide to NZ cattle farming’ has comprehensive tables of feed requirements. Handy feeding guidelines including pasture production in various areas of NZ is available on the FARMAX site at www.farmax.co.nz

The trick is to provide animals with enough feed to meet their ME requirements for the desired production level. It’s important to remember that feeding isn’t a precise activity but using available guidelines, and some simple rules of thumb, you should be able to get close to animal needs.

Examples of planned feeding of cattle,

as follows, can be the basis of plans for all cattle according to your particular situation.

The ready reckoner in Table 1 relating pasture drymatter to ME is a useful tool for your feeding plans. For example the amount of ME for beef cattle and their calves during early-mid lactation and grazing medium quality pasture on easy hill country would be up to 150 MJ ME each day. Reading from the ready reckoner this amounts to 15kg pasture DM.

Feeding for cow maintenance

Such a large quantity of feed consumed would require pastures about 12-15cm in length or 3000kg of DM/ha. To achieve the desired feed intakes these pastures would only want to be laxly grazed down to about 1200kg of DM/ha.

Similar feeding plans for cow maintenance, pregnancy and post-weaning growth of progeny can also be derived from published feeding tables and using the Table 1 ready reckoner (over page).

The amount of supplement offered will be pretty much a judgement call but can be guided by monitoring cow body condition score and/or liveweight. Maintenance of body condition score at about five during pregnancy in cows has huge advantages in both survival and viability of calves due to good early supply of milk.

For adult beef cattle during periods of pasture shortage several types of supplements can be effectively used. Silage is commonly fed to pregnant cows during winter. Requirements for 500kg cows during early-mid pregnancy are about 100 MJ ME per day. Good quality pasture silage will have a DM content of about 25% and contain 9 MJ ME per kg of DM.

To meet a pregnant cow’s daily requirement, ME needs to be a total of 11kg of DM or 44kg of wet silage is required, 2.2 tonnes per 50 cows. If a green pick is available in the paddock the quantity of silage fed can be reduced by 10-15%.

Pregnant cows are often break-fed forage crops such as rape during winter. An example calculation of the break size needed for 50 cows each day follows:

Maintaining body condition of five in 500kg pregnant cows, as above, requires 100 MJ ME/day or just over 8kg DM. Rape has about 12 MJ ME/kg DM. With an average yield of 7 tonnes DM/ha, or 0.7kg DM per square metre, this means each cow will need about 11.5sq m/day. To allow 15% trampling wastage, allocation will be 13.5sq m/cow or 675sq m/50 cows. If the feeding face is 75m wide then the electric fence will need to be advanced 9m each day.

These above example calculations give some basic pointers for working through your own feeding plans. For more help, including a FeedSmart App, go to B+LNZ at https://beeflambnz.com and search using ‘feeding calculator’.

• Ken Geenty is a primary industries consultant.