Keep those hoggets growing

01-05-2010 | Not Specified

Keeping hoggets growing, particularly in the first 50 days of their pregnancy, is important for later breeding performance according to Massey University sheep researcher Paul Kenyon.

Farmers are familiar with growing hoggets to a minimum of 38kg liveweight to maximise conception rates in hoggets but some fail to realise the importance of feeding the hoggets well in the first 50 days of pregnancy

"Many New Zealand farmers are disappointed with the liveweights of their two-tooths which have lambed as hoggets even though they appeared to be great hoggets at breeding and just prior to the lambing," Kenyon says.

Hoggets need to gain more than 20kg in total weight during pregnancy, including 12kg for the weight of conceptus (uterus, placenta, fluids and the foetus) to ensure each hogget is a good weight after giving birth.

"Many farmers get caught out and they find their hoggets weigh in the low 50kgs or even below at lamb weaning, and they have a lot of liveweight to gain before two-tooth breeding."

Ideally hoggets need to be growing at an average daily gain of 130-150g/day during the breeding period and throughout pregnancy to ensure they grow along with the foetus, Kenyon says.

With mature ewes, the traditional approach has been to maintain liveweight in early pregnancy and then to feed well in late pregnancy to ensure nutritional requirements of the pregnancy are met.

This approach will not work with hoggets because most of the nutrition in the last 50 days of pregnancy is being partitioned towards foetal growth and the young hogget herself will not be growing (two-thirds of the conceptus gain occurs in the last 50 days of pregnancy).

Instead she will be more likely to have birthing difficulty (large lamb but poorly grown hogget) and will be lighter than planned at weaning and below optimum two-tooth liveweight.

Liveweight gain during breeding and in the first 50 days of pregnancy has the biggest impact on lamb birthweight and weaning weight and the weight of the hogget at weaning, according to research data modelled by Dr Nicola Schreurs from Massey University. During this early period the nutritional requirements for pregnancy are small.

In comparison, liveweight gains in later pregnancy have much smaller effects.

It is important farmers make feed available during May to July to ensure their hoggets are gaining total liveweight gains of 130-150g a day.

In environments where herbage growth profiles do not allow for these relatively high hogget total liveweight gains, farmers need to consider if hogget breeding is really a viable option.

An alternative feed supply could be that a winter crop is used or extra feed is made available by reducing slightly mature ewe numbers (or another class of stock).

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