Evaluating Lamb Performance - project update

The post mortem results form the barren ewes sent on the 9/2/18 were very interesting and was a great insight to the flock health. The report showed that low to moderate levels of fluke remained in the ewes, and suggested that the rest of the flock may need to be retreated. Irwel decided to treat the low body condition score ewes with a flukicide. No gross evidence of pulmonary abscessation, OPA (Jaagsiekte), or MV and all animals seronegative for MV and Border Disease.

As ewes are not bloused with trace elements, taking liver samples to assess trace element status was something we were very keen to take advantage of. The results came back normal for Manganese, Selenium and Cobalt but Copper levels were marginal deficient and deficient therefore these levels were significant to justify supplementation.  

The metabolic profiling results from the 20 ewes 3 weeks pre-lambing were overall very satisfactory. An overview of the results is as follows-

Energy Balance

The most common marker used to determine energy balance is beta hydroxybutrate (BOHB). This is produced when fat reserves are being mobilised and non-esterified fatty acids (NEFA), (produced in response to an energy deficit, against an increasing foetal demand for glucose) is overwhelmed by the rate fat is being metabolised.

The group mean BOHB values for singles and fitter twin-bearing ewes (around BCS 3) were well below the threshold giving us confidence that the ewes were being fed according to foetal number. The BOHB levels in thinner twin bearing ewes were slightly higher but overall energy balance in thinner ewes were also satisfactory with 3 weeks before lambing. As a result, Irwel decided to group housed ewes in accordance to BCS with the hope that thinner ewes weren’t competing with fitter ewes for feed.

This shows the importance in achieving correct BCS at tupping and leading up to lambing as foetal growth has a high energy demand especially on low BCS ewes.

Protein status

All ewes sampled showed adequate overall daily intakes of Effective Rumen Degradable Protein (ERDP)

Albumin reflects long-term protein status, liver function and disease problems such as PGE, Johne’s disease and Chronic liver fluke. Some of the thinner twin-bearing ewes had low albumin results which could mean they may have some disease issues at the time of sampling or recently.

It should be noted that albumin is a long-term measure of protein status, and can take many weeks or even months to recover from previous disease problems. Therefore, when undertaking metabolic profiling it is important to bear in mind recent treatments the ewes have received.

Conclusion

In terms of current nutritional balance, the blood test results at 3 weeks off lambing are satisfactory, with group mean BOHB and protein status showing that all three BCS groups are having their current energy and ERDP requirements met, with ewes receiving 300grams of 32% high protein nut and grass silage ad lib.

There is a slight concern with the thinner twin bearing ewes not receiving the adequate energy as lambing gets closer, but with Irwel splitting the ewes into low and high BCS this will help ensure the thinner ewes get better access to the feed without the need to compete with strong ewes.

Overall Irwel was very happy with the outcome of the post mortems and metabolic profiling. We will continue to metabolic profile the ewes pre lambing next year as it gives a true reflection of the ewes current status on which management decisions can be made.