Wednesday, July 6, 2022

Condition key to success

The Southland Demonstration Farm near Wallacetown is on track to do 340,000kg milksolids (MS) for the year, a 25% improvement on three years ago. Total milk production, production/ha and production/cow have all increased dramatically during the past three seasons, DairyNZ business developer and member of the farm’s advisory group Howard de Klerk said at the farm’s summer focus day on February 7. For the 2010/11 season, production/ha was 1060kg MS and this year it should reach 1300kg MS/ha.  Production/cow was 363kg MS in 2010/11 and this year it will be 450kg MS. Although in the 2010/11 season late snow hit southern farmers hard and last year saw a January dry like no other experienced in the province in recent decades, de Klerk said the weather was not the major factor in the production increase.

“We had 1m of water through some parts of the farm in early January this year and parts of the spring were very cold so it has been no easier this year.”

Instead he said the continual improvement in milk production was due to “relentlessly targeting” pasture management, body condition scores and consistent and improved feeding.

“Not one of these alone was the silver bullet.”

Mowing benefits

With pasture management he advocated mowing pre-grazing in late spring.

“This controls quality while increasing intakes. If we don’t mow, the cows leave an untidy residual we have to fix by topping behind the cows. I’d rather mow in front than behind. When you mow behind you lose the pasture that has been left.”

He said cows could eat an extra 2kg dry matter (DM)/day if pasture was mown and wilted.

“So it kills two birds with one stone,” he said. “It increases intakes and top paddocks. We only do it when it is needed. It’s not a cop out.”

Pastures which were too long were “stepped over” and made into baleage.

During autumn, the focus was on making sure there was an average pasture cover of 2000kg DM/ha at the end of milking with a wedge of feed.  

“This ensures enough grass at the start of next season and reduces the amount of supplement required,” he said. “To achieve this, the last round in autumn begins on April 20 giving us a 40-day round length to finish the season.”

Nitrogen (N) has been applied more often and in smaller amounts, following the cows, than in past years giving good response rates and less chance of leaching.

Silage has been fed during spring when there is a shortfall of pasture and last autumn palm kernel was fed for the first time to achieve body condition scores (BCS) of no less than 4.5 to 4.75. The farm has proved it can put 0.5 BCS on during winter.

At the beginning of last April, cows with BCS of four or less were put on once-a-day (OAD) milking and offered palm kernel and cows with BCS 4.5 were kept on twice-a-day (TAD) milking but also offered palm kernel.

Diet adjustment

Transitioning cows onto and off winter crop has also been better managed to stop cows losing weight as they adjust to brassicas. About 90 tonnes, or 120kg/cow, of crushed barley has also been fed this season for the first time.

“While pasture is a fantastic feed, there are limits to what a cow can physically consume in a day as the time available and the bite size can impose a restriction of dry matter intake.”

De Klerk said data from the Lincoln University Dairy Farm (LUDF) showed cows could eat 18-19kg DM/day of grass.  

“For cows to maintain 2.2kg MS/day without losing too much weight requires around 20-21kg DM/day. Crushed barley was used to fill this gap to prevent cows losing too much weight and remaining in a negative energy balance for too long.”

He said when the 10-day daily protein percentage for the Southland herd was graphed for the past three seasons it showed protein started to lift at the end of October for this season while in past years it was in mid-January.

“The protein percentage trend in milk is often used as a good indicator of the cows’ energy balance. A dropping protein percentage usually indicates a period of negative energy balance while a gaining protein percentage indicates a positive energy balance.

“Getting the cows into a positive energy balance before mating is much better for reproduction than achieving a rising plane after the bulls come out.”  

De Klerk said feeding palm kernel and barley, although it helped, was not the only reason milk production had increased.

“If all of the barley fed had gone into only milk production if would have only resulted in a lift of 20kg MS/cow and the palm kernel potentially another 18kg MS/cow.”

Answer is in the genes

Even if dairy farmers chose to use only daughter-proven bulls for their herd mating, they were still benefiting from genomic-selected bulls, according to LIC general manager of genetics Peter Gatley.

“Genomic-selected yearling sires are breeding the bull mothers of tomorrow giving us a greater rate of genetic gain in the future,” he told the Southland Demonstration Farm focus day.

Genomics was “the biggest development since the invention of AI”.

Over-estimation of genomic-selected sires’ breeding worth (BW) was proving to be a worldwide problem and LIC were making adjustments which would see continual improvements. He also said genomic-selected bulls gave the country’s herd greater genetic diversity as more bulls were being tested and made available.

“If you are milking cows from genomic-selected sires your herd is four years more advanced than the guy down the road who is using progeny-tested bulls.”

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