Photosensitisation: much more serious than just sunburn.

Photosensitisation is where the skin becomes abnormally sensitive to sunlight.

Primary photosensitisation occurs due to animals consuming plants containing photosensitising substances such as Paterson’s curse, ragwort and heliotrope. Secondary photosensitisation occurs as a result of liver damage. Given the severe drought conditions and the influx of weeds, we have been seeing an increasing number of plant toxicities this season.

Symptoms include: redness, crusting and painful swelling of the skin. In sheep the face, ears and muzzle are usually the worst affected areas, however recently shorn animals can be affected anywhere on the body. In cattle, skin on the back, udder and areas of unpigmented skin are most affected.

Treatment commonly involves removing the animals from affected pasture, providing shade, anti-inflammatories and pain relief, antihistamines and in some cases antibiotics may be necessary. It is important to seek veterinary attention early, as death can ensue. The prognosis varies depending on the underlying cause and the severity of symptoms.

If you think your stock may be affected by photosensitization, please call us immediately - 63618388

Weaning is one of the most stressful events in the production cycle of beef cattle. When weaning is managed poorly the weaners lose weight and succumb to disease more frequently, which in turn increases the risk of them dying.

Conversely, however, when managed well, cattle continue to gain weight and the process increases the production system efficiency and maintains better cow condition.

The economics

+ Cows convert forage to milk at approximately 60% energetic efficiency (it takes ~5.5mj energy to produce a litre of milk, and milk is about 3mj/L)
+ Calves then convert 90% of the milk to lean tissue
+ This results in 54% (60% x 90%) energetic efficiency for the conversion of forage energy consumed by the cow into calf live weight gain.
+ As the calf gets older and the rumen starts to develop, this efficiency drops off substantially.

In summary, it is much more efficient to feed high-quality forage to a young calf, than it is to feed the cow to feed the calf.

When to do it

+ Weaning should routinely be done with calves down to 130kg, and under drought conditions down to 100kg.

Preparing for yard weaning

+ Managing numbers - batch wean if group sizes will be >100. 2.5m2 yard space is required per animal.
+ Vaccines (5 OR 7-in-1, BRD vaccines, Piliguard)
+ Drench – depending on worm egg count results which are reliable in grazing beef cattle from 4 months of age. Preferably use oral or injectable drench unless facilities are poor or fly/lice control is needed
+ High-quality pastures and nutrient dense feedstuffs
+ Fresh clean water – trough space 3cm/hd
+ Management of dust or mud in yards
+ Time for staff for daily handling during the weaning process
+ A set of scales to weight at the start and end of weaning

With most cattle throughout southern Australia being forced into confinement feeding, it is important to be on the lookout for bovine respiratory disease (BRD). This is a commonly occurring, multifactorial disease of intensification which can happen to all stock but is more frequent in weaners. The development of BRD is the combination of stress and infectious agents.

Stressors include: 

+ Transport
+ Lack of condition
+ Weather extremes
+ Co-mingling
+ Dehydration
+ Handling
+ Dust
+ Feed and water changes

Infectious agents include:

+ Viruses

- BHV-1 - Infectious bovine rhinotracheitis virus (IBR)
- BVDV (pestivirus)
- BRSV
- PI3 (influenza)

+ Bacteria

- Mannheimia haemolytica
- Pasturella multocida
- Histophilus somni
- Mycoplasma bovis

Of the above infectious agents, vaccines are available in Australia for BVDV, IBR and Mannheimia haemolytica.

Signs to look out for are:

+ Open mouth breathing
+ Nasal and oral discharge
+ Coughing
+ Drooping ears
+ Increased respiratory rate
+ Fever >39.3oC
+ Sudden drop in condition
+ Reduced appetite

Treatment

Treatment responses are good when the disease is detected early, and before severe damage has occurred to the lungs. A combination of antibiotics and anti-inflammatories are used along with isolation. Speak to us about this.

Impact on business

+ 70-90% of the cost of BRD is due to the reduction in weight gain.
+ There is a strong association between average daily gain and mortality rates due to disease
+ An increase in disease incidence and mortality rates will also reflect a decrease in average daily gains across the mob of cattle as there are animals among the group who are sub-clinically affected (not showing visible signs, but still sick).

It is understood that fertility is affected when sheep experience temperatures over 41 C for greater than 9 hours on the mating day or for 3 days after mating. This reduced fertility is due to early embryonic mortality. Given the extreme temperatures experienced in many regions in early January, many ewes are at risk of suffering embryo mortality.

Every ewe that slips one cycle because of heat stress needs another cycle to conceive. When heat waves occur during the mating period you should consider using a third or additional mating cycle as risk insurance. After an extended period of heat stress, producers should have their flocks pregnancy-scanned to identify non-pregnant and twin-bearing ewes, and plan re-joining the empty ewes in Autumn. Once producers have established which sheep have remained pregnant during this hot period, the producers should consider the effects of heat stress on the growth of the foetus.

If ewes are exposed to heat stress experimentally for the last 15 days of gestation, then the weight of the placenta and the foetus are reduced resulting in reduced rearing rates.

It appears that improving nutrition after heat stress is unlikely to improve the birth weights of growth-restricted lambs, although there will be improvements in lactation quality and in early post-natal growth. In the case of growth-restricted lambs, improved lactation is important for growth to weaning and subsequent weaner survival.