Cross Breeding

Choice of breeding system

Stephen Morris, Professor of Animal Science from Massey University, shares tips for crossbreeding systems for commercial beef breeding cow herds.

Crossbreeding is an established breeding method used in sheep and beef cattle breeding to increase productivity. It has been used throughout the world and there is ample evidence to support the production gains possible from crossbreeding.

However, not all crossbreeding systems maximise these theoretical gains, some are too complicated, difficult to implement under commercial hill country conditions and especially in small herds. The challenge is to identify appropriate crossbreeding systems that are simple and easy to operate in commercial beef breeding cow herds. Note that crossbreeding is not a cure for inferior management and cannot replace the need for continued selection policies in our pure-bred herds.

There are two basic breeding systems. If the source of replacement females is heifers produced from within the herd then this is called a continuous system. If heifers are not put back in the herd this is a terminal system. In a continuous system since replacement females are retained in the system the cowherd has genetics of both sire and dam traits.

Therefore, if sires have traits that are undesirable in cows, they cannot be hidden in a continuous system. In a terminal system replacement females are purchased. This offers more flexibility in choice of genetic types enabling specialized maternal and sire lines to be used.

A combination of relatively small dams (e.g. Angus cross Jersey) bred to large sires in a terminal system fully exploits breed complementarity. For example, crosses between beef and dairy breeds can be used to produce cows that, when fed suitably, have superior milking and reproductive ability.

Mating these animals to terminal sires with large mature size and high growth rates (e.g. Simmental) allows slaughter offspring to be produced with the benefits of growth rate and leanness to attain heavy carcass weights while maintaining smaller, highly productive breeding cows. In this way, the breeds can be chosen to complement each other in a manner not achievable with straightbred animals. This is probably the best reason for using crossbreeding.

The benefits resulting from crossbreeding are best achieved through increased fertility of crossbred cows and growth rate of calves.  In Figure 1, it can be seen that if straightbred cows reared crossbred calves rather than straightbred calves, on average, there would be an extra 8.5% increase in weight of calf weaned per cow mated (e.g. for a 200 kg weaner this would equate to 17 kg of extra calf weaning weight).

If crossbred dams were then used to rear the crossbred calves, a further 14.8% increase could be expected as a result of the better maternal environment (due primarily to fertility and milk production) provided by the crossbred dams. Using crossbred dams to rear crossbred calves, the expected extra calf weight weaned/cow would be 23.3% compared to straightbred cows rearing straightbred calves. The monetary increase from this at current prices is $115.00 (Table 1).

 

Figure 1. A comparison of % increase in calf weight weaned/cow exposed to breeding, as a result of mating either straightbred cows to bulls of a different breed (centre), or mating first cross cows to bulls of a third breed (right).

 

M = Maternal heterosis due to the dam being a crossbred

I = Individual heterosis due to the turnoff animal being a crossbred

 

* Results were obtained from an experiment involving all relevant crosses among Hereford. Angus and Shorthorn cattle.

 

By adopting a policy of buying-in all heifers, 100 percent of the cows in the herd can be mated to a terminal sire. A common system used by farmers is the purchase of Beef x Dairy cross heifers (Hereford x Friesian or Angus x Friesian) as weaned calves, mating these at 15 months to an easy calving sire breed (e.g. Angus, Hereford, Murray Grey) and from then on to a larger terminal sire breed (e.g. Simmental, Charolais, Limousin or South Devon).

The main disadvantage of this system is the need to organise a reliable source of replacement heifers.  Some farmers solve this by having formal arrangements with dairy farmers whereby they purchase appropriate sires for the dairy farmer and then contract to purchase the female and sometimes male progeny back.

 

Table 1. Percentage of maximum heterosis expected in progeny for various mating systems.

 

 Mating system Heterosis retained Superiority over parent breeds
Individual (%) Maternal (%) Weight of calf
Weaned / Cow mated
(%)               (kg)
Value at $2.50/kg LW
 Straightbred A x A 0 0 0 200 0
 2 breed cross (A x B) 100 0 8.5 217 42.50
 3 breed cross (A x B) x C 100 100 23.3 246 115.00

 

There is no doubt that the more productive crossbred type cows are often heavier (although not always if for example a beef breed cross Jersey breed cow is used) and will therefore require extra feed. Winter feed requirements can limit the number of beef cows able to be run in a hill country grazing beef herd.

It should also be notedthat in hard hill country with large paddocks where the beef breeding cow is the pasture control mechanism and her body condition is the “supplement” to get through feed deficit periods the British breeds may be more efficient at this weight gain over summer and controlled weight loss over the winter.  In these types of environments mating heifers at 15 months may not be adopted and hence the reproductive advantage of beef breed cross dairy breed cows may not be realised.

In Table 2 the annual feed consumption (kg dry matter/head/year) for three different cow liveweight types (small, medium and large) are calculated. The different cows are assumed to wean claves at a liveweight equivalent to 50% of their dam autumn live weight. If each of these cows rears 50% of their own autumn liveweight to sale as weaner calves they are all are equal in terms of $ return per kg of feed eaten and/or per stock unit.

If we considered these three types of cows were run on a farm where there was a fixed amount of feed, then 100 cows of the small type, 92 of the medium and 79 of the large type cows could be farmed. This table illustrates that there are a range of cow types that can give similar productivity and returns.

 

Table 2. Seasonal liveweights and production data for three different beef breeding cows type

(note liveweights excludes the weight of conceptus).

 

 Small  Medium  Large
 Weaning (kg)  430  470  550
 Mid-winter (kg)  380  420  500
 Pre-calving (kg)  380  420  500
 Mating (kg)  410  450  530
 Calf wean wt (kg)  215  235  275
 Feed eaten kgDM  2880  3131  3657
 Stock units  5.2  5.7  6.6
 $Return/kg feed  0.186  0.187  0.187
 Number of cows  100  92  79
 $GM/Stock unit  105  107  108

 

Therefore when a farmer is considering a change from straightbreeding to a crossbreeding system the following points need to be noted.

  1. Crossbred cows will wean heavier calves.
  2. Crossbred cows will have better reproductive performance if mated as yearlings.
  3. Crossbred cows will return more if cow live weight is not increased substantially.
  4. There is a range of crossbreeding systems suitable but to obtain maximum benefit the system needs to be carefully planned and implemented
  5. If feed management is not up to scratch then the benefits may not be greater than those achieved by the use of the traditional British breeds.
  6. There are now premiums being offered for straightbred Angus, Hereford and other British breeds which could negate some of the advantages of crossbred animals.

It is the last point that is relevant today where some supply chains are offering premiums for breed specific branded beef products. If these schemes result in premiums being paid for calves of these breeds at weaner sales and these premiums can generate returns for cow calf producers at weaning similar to those given in Table 1 then there would be no need to change form a straightbreeding system to a crossbred system of breeding.

The premium for a 250 kg live weight straightbred Angus weaner would need to be 17 cents/kg live weight to equal a two breed cross weaner and 46 cents/kg live weight to equate to a three breed cross weaner (i.e. 267 and 296 cents/kg live weight compared to the base price used in table two of $2.50/kg live weight.)

Assuming the live weight advantage continues through to slaughter age then these premiums would need to be at least at this level or above at slaughter. Therefore an Angus steer at slaughter would need a premium in excess of 46 cents/kg carcass weight to match the extra live weight gain generated from a three breed cross animal. This calculation takes no account of the extra feed required to achieve this gain.