Cobalt deficiency is recognised as a problem in several areas of Australia. Some coastal sandy calcareous soils are known to be cobalt deficient (Caple and McDonald, 1983) but cobalt deficiency has also been reported on granite soils on the New England (Duncan et al, 1986) and we have a small area of light granite east of Bathurst that is also cobalt deficient. However, commercial interests have advocated the use of Vitamin B12 alone or incorporated into vaccines, across a much wider area of NSW. When Lyndhurst sheep producer Greg Emms challenged us with the idea that his lambs would probably respond favourably to vitamin B12, Jeff Eppleston and I combined with Greg to examine this. We conducted a response trial in which half of a mob of crossbred lambs was treated with vitamin B12 at lamb marking. Lyndhurst, about 50 km southwest of Bathurst has no known history of cobalt deficiency.
As previously described (Watt, Eppleston and Emms, 2009), Merino ewes were joined to Border Leicester rams for 6 weeks to lamb commencing on 7 July 2008. At marking on 27 August 2008, approximately 800 lambs were tagged with individually numbered ear tags and those given even-numbered tags received a 1 ml subcutaneous injection of Vitamin B12 (Novartis Vitamin B12 Cobalamin Complex Injection for sheep and Cattle, containing 1.72mg/mL Hydroxocobalamin and 0.2 mg/mL Cyanocobalamin). The odd-numbered lambs were left untreated. In addition, each lamb was vaccinated with 6 in1, Scabigard and Gudair. The lambs were weaned on 10 November 2008, divided into ewes and wethers run in two groups on a crop of forage brassica. The wether portion was weighed on 17/12/08 when they averaged 5 months of age.
Five lambs were blood tested to establish their vitamin B12 status at the start of the trial. Vitamin B12 levels averaged 1660 pmol/L and ranged from 660-2401 pmol/L. The normal range quoted is 400-5000 pmol/L.
There was no difference in live weight between B12-treated and untreated control lambs (Table 1).
|Vitamin B12 group||Number||Live weight (kg)|
|Treated||193||33.8 - 0.3|
|Untreated||197||33.7 - 0.3|
|Total||390||33.8 - 0.2|
We considered that a vitamin B12 response trial was justified because commercial interests had marketed use of vitamin B12 across the tablelands to improve growth rates and well-being. In the absence of hard data, it is difficult to enter the discussion about whether sheep or lambs in this district respond to vitamin B12. A single response trial only reflects the situation on one farm and in one season. However, in this case it supported our expectations that are in part backed by blood tests from a range of flocks and herds across the tablelands. The results of these blood tests and this trial have enabled us to participate in the debate on the requirement for vitamin B12 in our area.
It is fortuitous that we chose to weigh the wether portion of the lambs in light of the findings of Shallow, Ellis and Judson (1989). These authors somewhat surprisingly found a significant response to vitamin B12 in wether lambs but not in their female cohorts. While difficult to explain, this sex interaction was seen on three of four occasions. Shallow et al (1989) noted that others have also reported this finding in prime lambs, young cattle and rats. Interestingly, Duncan et al (1986) commented that steers and young bulls were most severely affected in the case they reported.
Commercial interests no doubt find it tempting to value add their products and to merchandise additional products to cater for livestock producers who desire to ensure that all reasonable steps are taken to ensure the health of their animals. Vitamin supplementation is relatively inexpensive and perceived to be harmless even if unnecessary. However, mineral and vitamin supplementation is not always without consequences. Vitamin injections can cause site reactions and anaphylaxis is possible. Mineral overdoses are potentially toxic.
This trial demonstrated that at least for this year and this mob of sheep on this property, vitamin B12 supplementation was unnecessary. It also supported the contention that a response to vitamin B12 is unlikely in a flock with adequate blood vitamin B12 levels.
We would like to acknowledge the contribution of Greg Emms who suggested that the trial was warranted and provided the lambs for the trial.