Friday, March 29, 2024

Health benefits from SGL

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Using short-gestation length (SGL) semen at the end of AI not only means cows calving on average 10 days earlier the following spring but also the potential to reduce the animal health bill, LIC’s SGL breeding programme manager Malcolm Ellis says.
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“If you keep using AI and SGL semen, instead of using bulls, potential reductions in animal health costs can be one of the many benefits. 

“You are getting cows calving earlier which means they have more time the following year to get back in-calf so reduced intervention can be a positive spin off, which is another cost-saving,” Ellis said.

A growing number of dairy farms in New Zealand were run as closed herds, he said, and the introduction of bulls each mating season created a vector for diseases like Bovine Viral Diarrhoea (BVD).

“We’ve seen a spike in the past 12 months of BVD positive tests from bulk milk testing and it might be because farmers are not bothering or wanting to pay for bulls to be BVD tested at the moment. We don’t know. But it’s a risk farmers don’t need to face.”

BVD caused reduced milk production, lower body condition scores, abortions and possible death in cattle.

As well as spreading disease, bulls could also injure cows when riding them, causing displaced pelvises and broken legs.

Ellis said there were also health and safety issues for staff.

“When we talk about getting bulls off farms, or running less bulls by using SGL semen, most of the onfarm staff we meet are pretty keen on it. Some of them are over the moon that they don’t have to deal with bulls.”

He said bull fatigue was an obvious problem on NZ farms.

“I look at the fertility focus reports and immediately after the bulls go out there is an increase in the conception rates, because the bulls may be picking up the cows with silent heats and bringing cows on, and then at about day 10 to day 12 there is a huge drop off and we think that is bull fatigue.

“If you look at a 500-cow herd that uses AI for four weeks with an 80% submission rate and a 60% conception rate, which is the national average, that means there are 234 cows not pregnant at the end of AI. That means there are 12 cows cycling each day for the bulls to mate.

“I believe overworked bulls could well be the biggest contributing factor to our unacceptably high national empty rate.

“Tagging three weeks of SGL on to the AB plan would reduce the work load for these bulls to 5.5 cows cycling each day.”

He said large numbers of bulls, as well as riding cows, were fighting and getting hurt, damaging fences and gates.

“They can’t do all that and still get cows in-calf.”

SGL semen was available in fresh as Kiwicross and frozen in Jersey, Friesian and Hereford through LIC this mating season.

“From next year we will be having SGL Hereford available in fresh throughout the country for the first time so farmers can use it right from the start of mating over their low BW cows to create an income stream connected to the favourable beef schedule, or purely for its short gestation length later in the mating season.”

He said farmers should not keep the progeny of SGL matings for replacements for their dairy herd, because the BWs of the resulting calves were low. Using Hereford as a marker for a period between standard AI and SGL sorted out management problems because Hereford-cross calves had distinctive white faces.

“If you select SGL Dairy then you may well have to consider putting some management practices in place to stop mis-mothering so the right calves are kept as replacements.”

During the 2014 mating season 3500 farms included SGL products in their mating plans and Ellis said LIC expected this number to keep growing. 

“We have to get our national empty rate down. Something has got to change. It is too big a cost to the industry. 

“SGL will not be the total answer but it is a valuable component to the solution.”

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