CASE NOTES

VITAMIN B12 IN SHEEP ON THE NSW SOUTHERN TABLELANDS

Bill Johnson, District Veterinarian, Goulburn

Posted Flock & Herd March 2011

Introduction

Vitamin B₁₂ is essential for normal growth in sheep, and is produced from cobalt in the rumen. Depending on the severity of the deficiency and age of the animal, vitamin B₁₂ deficiency may be associated with a range of clinical signs, including reduced appetite, failure to thrive, reduced growth rate and wool production, anaemia, and weeping eyes.¹

Cobalt deficiency has not been recognised in soils² or in animals in the Goulburn area of the Southern Tablelands of NSW, yet there are claims locally that supplementing with vitamin B₁₂ improves sheep productivity.

Vitamin B₁₂ is available by injection, either alone or in combination with vaccines or anthelmintics. A dose of 2mg hydroxocobalamin by subcutaneous injection protects young sheep from depressed weight gain due to Vitamin B₁₂deficiency for up to 14 weeks, although plasma B₁₂ levels may begin to decline within two months.³

Parenteral products containing Vitamin B₁₂ are readily available in rural merchandise stores throughout the district, and are widely promoted to sheep graziers. The addition of vitamin B₁₂ increases the cost of a six antigen vaccination for sheep by about 95%, or by about 21c a dose.⁴

Results of an unpublished trial run in spring of 2007 in second cross lambs on a property at Gurrundah, 25km south of Crookwell, have been used by local rural merchants to support the sale of B₁₂ products. This treatment-control trial of a couple of hundred lambs at marking reportedly showed a two kilogram advantage in favour of B₁₂-treated lambs at weaning.⁵

The trial results were supported by the pub talk here, that B₁₂ supplementation at marking causes lambs to heal up more quickly after mulesing, eliminates the tail in the mob at weaning, and reduces flystrike.

ON-FARM TRIAL

A second treatment-control trial was conducted on a property at Bannister, 17km south of Crookwell in spring 2009. The 232 Merino x Poll Dorset lambs were randomised into two groups prior to marking, at six weeks from the start of lambing. Half the lambs were vaccinated with Glanvac6^® (Pfizer Animal Health) while the other half was vaccinated with Glanvac6 B₁₂^® (Pfizer Animal Health). The lambs were weighed 14 weeks later.

There was no statistical difference in liveweight between the two groups. The fact that the control group average was 0.6kg heavier than the treatment group highlighted the need to have either a much larger sample size, or to weigh all lambs both at the commencement and end of such a trial. Growth rate of these lambs reflected seasonal conditions, with a lower than expected growth rate of 210g per head per day.⁶

DISTRICT VITAMIN B12 SURVEY

Four of thirty four cobalt supplementation trials in lambs in Western Australia produced a beneficial outcome. Responses were reported only on grass-dominant pastures in spring after above-average winter rainfall.⁷ With this in mind, vitamin B₁₂ levels in crossbred lambs were measured on properties representative of the majority of soil types and localities in the Goulburn district at the end of spring 2010.

Spring pasture growth in the survey area exceeded normal in 2010. Legume content of the mainly improved pastures was negligible following years of drought conditions in the area. Blood samples were collected into lithium heparin tubes from ten crossbred lambs on ten properties at the time of weaning, as determined by each flock manager. The lambs varied in age between 14 weeks and 24 weeks. Breeds represented included second cross (BL/M x PD, BL/M x WS) and first cross (M x PD, Dohne x WS). Lambs were yarded on the day of sample collection, as fasting can increase B₁₂ levels.¹ Vitamin B₁₂ is light-sensitive; samples were protected from light and consigned to the laboratory to arrive within 24 hours of collection.⁸ Only flocks where lambs had not received supplementary vitamin B₁₂were considered for the survey.

Vitamin B₁₂was determined by modified ECLIA by Regional Laboratory Services, Benalla. Results were reported in pmol/L. The normal range for B₁₂ is reported to be between 400 and 5000 pmol/L; marginal levels are between 200 to 400 pmol/L, with deficient less than 200 pmol/L.⁸

The one hundred samples submitted returned B₁₂ levels between 511 and >3100 pmol/L (Table 1). Only six of the samples tested had plasma B₁₂ readings below 1000 pmol/L.

Flock	Lamb breed (Dam x sire)	Predominant soil type	Location relative to Goulburn	Approximate age oldest lambs (wks)	Average B₁₂ pmol/L	Range B₁₂ pmol/L	# samples <1000 pmol/L
A	BL/MxWS	Grey loam	15km W	20	2097	1271-2693	0
B	D x WS	Shale	30km W	15	1530	511-2219	2
C	MxPD	Granite	55km SW	18	1590	1000-2213	0
D	MxPD	Basalt	37km NW	14	2842	2499->3100	0
E	BL/MxPD	Shale	10km S	17	1390	818-2068	2
F	BL/MxWS	Basalt	60km NE	24	2605	1590->3100	0
G	BL/MxPD	Basalt/granite	70km N	18	2522	1557->3100	0
H	BL/MxPD	Alluvial	35km E	18	1293	861-2184	2
I	BL/MxPD	Basalt/granite	40km SE	17	2093	1408-2937	0
J	BL/MxPD	Basalt/quartz	37km WNW	16	1874	1103-2656	0

Table 1. Vitamin B₁₂ sample results for lambs from ten Southern Tableland flocks

Discussion/CONCLUSIONS

Involvement in the small treatment trial highlights the need to have a substantial sample size for significant results (discussed further in these Proceedings by Helen McGregor).

The plasma B₁₂ levels reported could be correlated with a treatment response trial to determine if the growth rate of lambs with vitamin B₁₂ at the lower end of those results in the survey would improve with B₁₂supplementation.

The gender of the lambs sampled was not recorded. The mobs sampled were mixed sex, with both genders sampled on all properties except G, where only ewe lambs remained. Wethers are reported to be more susceptible than ewe lambs to B₁₂ deficiency.⁹

Based on the accepted laboratory lower limit of normal Vitamin B₁₂, no sheep in the mobs tested was vitamin B₁₂ deficient, despite being raised in a bountiful spring.

Acknowledgements

Elizabeth Patrick BVSc provided the opportunity and technical support for the Vitamin B₁₂ survey. Pfizer Animal Health funded the laboratory tests, and Tablelands LHPA funded the sample collection. Ten willing tablelands graziers provided the sheep and facilities for B₁₂ sampling.

References

Radostits OM, Gay CC, Hinchcliff KW, Constable PD Veterinary Medicine 10th Edition pp 1701-3
Peter Simpson, former District Agronomist, NSW DPI pers comm.
Judson GJ, Babidge PJ (2002) Vitamin B₁₂ injection for preventing cobalt deficiency in lambs Australian Veterinary Journal 80:777-778
www.generalvet.com.au enquiry Feb 2011
Roger Willoughby, Gunning Rural Supplies pers comm.
DV Goulburn, results of unpublished field trial
Higgs A (2004) Trace Element Deficiencies in Sheep and Cattle. WA Department of Agriculture, Farmnote 8/2004
Vitamin B₁₂ assay information sheet. Regional Laboratory Services, Benalla, 2010
Shallow M, Ellis NJS and Judson GJ (1989) Sex-related response to vitamin B₁₂ and trace element supplementation in prime lambs Australian Veterinary Journal 66:250-251

Abbreviations

ECLIA Electrochemiluminescence immunoassay

Glanvac6^® Multicomponent adjuvant vaccine against Corynebacterium pseudotuberculosis, Clostridium perfiringens type D, Cl. tetani, Cl. septicum, Cl. novyi, and Cl. chauvoei

pmol picomole (mole^-12)

Sheep breeds: BL border leicester, D dohne, M merino, WS white suffolk, PD poll dorset