Bull Management

‘Rule of thumb’ is to have 1 sound bull to 30 non-pregnant cows. Ideally there should be two teams of bulls and these should be changed every second day.

A bull is capable of mating up to 3 cows a day before semen quality drops. The daily work rate in most herds will be the same after the 3rd week as it is in the 5th week as the number of cows coming on heat on a daily basis will be similar. Like-wise the work rate will be similar between the 6th week and the 8th week.

Therefore in a 700 cow herd which is doing 4 weeks of AI, they will need (based on 3 weeks of mating):

• 700 cows x 82% submission rate x 52% conception rate = 300 pregnant,

• this leaves 400 non-pregnant, which requires 13 sound bulls in the herd at all times

In a 700 cow herd which is doing 6 weeks of AI, they will need:

• 700 cows with 65% 6 week-in-calf rate = 455 pregnant

• This leaves 245 non-pregnant, which requires 8 sound bulls in the herd at all times.

Bull numbers in general can be reduced by about 40% at the end of each cycle. Remember to ensure that bulls have been both vaccinated and tested clear for BVD.

Coccidiosis Prevention of Calves

We often see coccidia outbreaks in calves that are greater than 4 weeks of age that still aren't eating enough meal (<1kg per day). However the other time we see coccidia problems are when calves have the meal removed after weaning. The coccidiostats in calf meal inhibit coccidia growth, when the meal is removed the coccidia will continue their development and complete their life cycle which can result in disease. Trial work in NZ has shown that calves treated with Toltrazuril (Toltrox) when meal is removed are 3-5kg heavier 5 weeks post meal removal than those that aren't treated. This was in an environment with a relatively low coccidia burden. A lot of our farms will have much higher burdens than this so perhaps we could expect even greater weight gains. If you have had calves in previous seasons that just don't do well when meal is removed it would be advisable to consider the use of Toltrox in calves at calf meal removal.

Fractures in Heifers

Over the last 10 or so years, there has been an increase in the number of cases regarding heifers with fractures in their front legs and in particular, the humerus. Keren Dittmer is a Veterinary pathologist at Massey University and is researching this syndrome along with two PhD students. She is requesting bones from affected animals to be sent in in order to understand this better. The bones are CT scanned to look at densities; so far the affected heifers have smaller, thinner and weaker bones compared to their counterparts. Affected properties can also participate by completing a questionnaire about the farming system. Furthermore, additional farms are being sought to participate by enrolling into another study and being followed over the next few years to see if any risk factors can be identified or not.

Overall, this syndrome is poorly understood due to the nature of the presentation. Fractures are seen as 2 year old and less commonly as three year olds but current research indicates that the problem arises whilst the heifer is developing her bones.

2 syndromes need to be differentiated:

• “Rickets” type = defective bone mineralisation. This is seen in some heifers that are fed fodderbeet which is low in phosphorus. Bones are weak and at a higher risk of fracturing. It is important to supplement heifers with an appropriate phosphorus source whilst on fodderbeet.

• “Osteoporosis” type = reduced quantity of a normal bone quality. Again, the bone is weaker and therefore more susceptible to fractures. The most significant reason for this is a feed shortage but can sometimes be associated with copper deficiency, calcium deficiency and parasitism.

We are interested in collecting samples for further research. Please contact us if you think you have a case.

Calf Disbudding - Changes for 2019

The calf sheds are filling up which means that disbudding is just around the corner.

• The new welfare regulations which require all calf disbudding to use local anesthetic don't come into effect until October 2019. So you are still able to disbud without local this season as long as it is completed prior to this date.

• If you are wanting to disbud your own calves using local anesthetic there is a requirement to go through a training and accreditation process with one of our vets. MPI may conduct an audit to ensure compliance. If you haven't booked this in yet, please contact the clinic now as we are wanting to complete on farm accreditations by the 14th August.

• This year we are using a new product Tri-solfen on all calves we disbud. Clinical trials have shown that Tri-solfen significantly reduces pain after disbudding and results in greater average daily weight gains after disbudding.

Reducing Disease & Deaths in Newborn Calves

There is nothing more demoralizing than a pen of sick and dying calves. This frustration is even greater when you appear to have done all of the right things; cleaned out pens, vaccinated the cows, fed high grade colostrum, isolated sick calves, and so on!!

A recent New Zealand trial looks to have shown a potential new tool for these situations. The trial looked at the effects of giving calves a 0.75ml injection of MultiMin within 24 hours post birth. MultiMin contains zinc, manganese, selenium, copper, and chromium. Overseas studies had previously shown reductions in disease and mortality after supplementation at this stage, and this trial backed up these findings.

This trial showed marked reductions in disease morbidity and mortality between 3 and 35 post calving, with the MultiMin group having a 66% reduction in the odds of scouring in that period compared to the control group. At this stage the mechanism of action is unknown, but it is likely that there is a direct effect on the immune system. There are plenty of articles looking at the involvement of zinc and copper in immune function, and other trials with MultiMin in challenge situations with BVD that showed faster rises in antibody levels in calves given MultiMin.

Treating calves with MultiMin could be incorporated into the daily routine, with calves being injected as they arrive in the shed, and give your newest arrivals the best start in life.