Silage basics

Utilising silage pays for feedlotters and dairy farmers, but the process has to be managed well, says Gerhard Uys.

Silage basics
- Advertisement -

Silage is fermented, high-moisture forage made from crops and fed to grazing livestock.

After the crop has been harvested and chopped up, it is piled high in a silo or pit, compressed to exclude air, and covered with a plastic sheet.

Anaerobic fermentation starts approximately 48 hours later, converting sugars to acids, and takes about two weeks to finish.

- Advertisement -

Speaking at a recent Alzu hay day near Middelburg in Mpumalanga, Kenneth Botha from Nutrigenics shared the three silage myths commonly believed by South African farmers:

  • Dairy cows do not do well on a high level of silage;
  • Heifers can only eat silage after six months of age;
  • Sheep cannot eat silage.

Botha points out that in Europe, heifer calves are fed grass silage after four days, while in the US, heifer calves are given silage mixes after weaning age and cows are fed up to 34kg silage/day.

Silage, he says, is cheaper than calf feed and a lucerne mix. On heifers, a farmer can save up R230/day on feed costs. Sheep, except for pregnant ewes, do well on silage.

A word of caution
For silage to make economic sense, however, the contents should be varied and fibre intake must be well-managed. This is especially true of starch in dairy cows. If not managed properly, it can cause milk production to fluctuate.

“In a high-producing milk cow, the digestibility of starch can make a 4,6l/ day difference,” Botha says.

He cautions farmers to reduce as far as possible the dust in silage, recalling how some entrants in a recent silage competition had 30% sand or ash in their maize silage.

This directly affects milk production. He cites a study which found that a 10 000-head feedlot could increase its meat output by 27t per cycle if the feed was well-managed and free of contaminants.

Aerobic activity
Dr Chris van Dijk, CEO of the Milk Producers’ Organisation, adds that silage has to be properly cut and stored. “Make sure that silage is free of manure and dead animals such as rats, as this can lead to Clostridium botulinum poisoning,” he stresses.

Stable silage depends on a quick decrease in pH to an optimal level, preservation of water- soluble carbohydrates, and minimising aerobic activity, explains Van Dijk.

“Unstable silage can lead to liver abscess and faecal infection, diarrhoea and death. Listeria monocytogenes is also a problem on the outer layers of silage, where oxygen contact occurs. This could lead to abortion.”

Airborne yeast and fungi in spoilt silage affect respiratory systems and cause an intake of mycotoxins, leading to a low conception rate and immune-related diseases.

Summing up the process, Albert van Rensburg, managing director of Biomin Animal Nutrition, emphasises the need to take full control of fermentation in silage production. Silage, he explains, is a process of losses and feed quality does not improve with ensiling.

“Success in silage is based 90% on basic principles such as management, compacting, sealing and chopping lengths,” said Van Rensburg.

BONUS: Watch Argentinian cattle farmer explain the feeding process from a silage bag