Suckler beef producers need to function at maximum efficency if profitability is to be achieved. For the breeding herd, the key is to maximise reproductive efficiency.

The single most important parameter in measuring production efficiency in the beef cow herd is the calf output produced annually from each cow that is mated.

A spring-calving suckler herd is reproductively efficient when the calving interval is 365 days, 90% of the herd calves in 10 weeks and less than 5% of the herd is culled for infertility.

However, data from ICBF shows that, on average, nationally, suckler cows are producing only 0.80 calves per cow per year and have calving intervals of greater than 400 days.

These results clearly imply that there is a need for enhanced reproductive management at farm level if the true production potential of the suckler herd is to be realised.

Furthermore in an Irish context, suckler systems are predominantly spring-calving and grass-based (calving date match to onset of the grass grazing season).

To maximise the proportion of grass in the overall feed budget of the system, cows need to conceive during a defined breeding season and obtain high reproductive performance.

Improved reproductive efficiency in suckler herds

To improve reproductive efficiency (leaving aside genetics) in suckler herds, the two main factors the farmer must focus on are (i) the interval from calving to first heat (post partum interval), and (ii) conception rate.

There is no substantial evidence of a decline in conception rate of beef cows, and typical conception rates of 60-70% are achievable to either AI or natural service, unless there are problems

with semen quality, AI technique or bull fertility.

The interval from calving until the re-initiation of estrous cycles, often referred to as postpartum anoestrous interval (PPI), has long been recognised as the primary factor reducing reproductive efficiency in beef calf-cow operations.

On average, beef cows and first calving heifers have a calving to first ovulation interval of 50-55 days and 60-70 days respectively.

However, it is important to acknowledge that, between herds, that this interval can vary from anything from 30 to 180 days.

For seasonally calving beef herds to maintain a 365 day calving interval, the aim must be to achieve conception within 75-80 days (or two to three oestrus cycles to get the cow back in calf) following calving.

Remember that each day that a cow fails to go back in calf is estimated by ICBF to cost €7.50. The length of the anoestrous period is governed by many factors but is primarily influenced by:

  • the nutritional status of the cow (both pre-partum nutrition and plane of nutrition post calving), and
  • maternal off-spring bond that exists between the dam and her calf.
  • Body condition scoring

    Cow body condition scoring (estimate of degree of fatness on the cow’s back) is a practical management tool that farmers can use to monitor the nutritional status of their cows.

    A series of target condition scores can be used to manage the cow’s feed requirement, thereby ensuring that cows are in the correct condition at the key stages of the production cycle, namely weaning, calving and particularly breeding.

    Target BCS for spring calving cows are summarised in Figure 1. Ideally, a spring-calving cow should be housed at a BCS of 3 to 3.25.

    Over the winter period, the cow can utilise some of her body reserve (0.75 BCS) to calve down at a BCS 2.25 to 2.5. Post-calving, the goal is to gain body condition (establish positive energy balance) towards mating.

    The manipulation of the cow’s body condition between winter and summer is an important strategy in controlling feed costs in suckler production. In brief, charting body condition score can be used to plan feeding management through the year so optimum cow reproductive performance is achieved at minimum feed cost.

    Nutritional requirements of the lactating suckler cow

    The most critical time period to manage cow nutrition is from six weeks before calving through to six weeks after breeding. The freshly calved cow faces many competing demands. If dietary energy intake is inadequate, this is one of the key factors limiting reproductive performance of the cow.

    For example, the energy required for reproduction and to initiate oestrous cycling after calving is only available after requirements for maintenance, growth, and milk production have been met.

    Energy in cattle nutrition is measured in units called UFL where 1.0 UFL is equivalent to 1kg of air-dry barley. Energy in all other feeds is related to this.

    Compared to dry cows, the lactating suckler cow rearing one calf requires over 1.5 times greater feed requirement. Suckler cows with higher milk production also have higher feed requirements (0.45 UFL per litre of milk produced).

    Typically, cows of the more continental beef breeds produce five to eight litres of milk/day indoors and, therefore, a 600kg cow needs 7.8UFL to 9.1UFL per day while maintaining body condition.

    Feeding options of cows post-calving

    Prior to and during the breeding season, it is critical that the nutrient supplied by the diet is sufficient to meet the requirement of the cow.

    Post-calving, the diet offered to the suckler cow should be based on five key factors:

  • nutrition status of the cow estimated by the BCS at calving;
  • the diet quality available;
  • timing of calving;
  • cow age;
  • cow type or milk production potential.
  • To ensure high cow performance, farmers should adjust the post-calving diet accordingly to account for variation in these factors.

    Visit www.farmersjournal.ie again next weekend to discover four diet options to suit each situation.

    *Alan Kelly is a lecturer in Beef Production and Nutrition at the School of Agriculture and Food Science, University College Dublin.