Achieving MSA premiums during summer
04 January 2016
The national average compliance to MSA minimum requirements for grassfed cattle in 2014-15 was 89.4%. The main reason for non-compliance was due to high pH (greater than 5.71) and/or dark meat colour (greater than AUSMEAT colour 3).
Regardless of any other carcase attributes, failure to meet pH or meat colour requirements rules out achieving any MSA monetary premium that may be on offer for the carcase. Given that during the same period the average over-the-hooks MSA premium for yearling cattle was 33¢/kg, this non-compliance cost producers $91/head.
The period leading into summer is one of the critical times of the year to ensure cattle are well prepared to meet MSA requirements, as this is the time when the nutritive quality of pastures can rapidly decline.
Holes in the bucket
Energy is stored in muscles as glycogen. The analogy of a glycogen bucket to represent the mount of glycogen in the muscle is a useful tool for considering the condition of cattle being consigned to MSA and optimising compliance to MSA requirements.
The bucket of glycogen fills up through good quality feed that promotes a rising plane of nutrition over time. Once the animal has been slaughtered, the glycogen remaining in the muscle is converted to lactic acid, which creates low pH. At low pH, the meat is likely to have a desirable colour.
Glycogen, however, is rapidly reduced by holes in the bucket created by stress and this can happen in a matter of minutes. If the animal is slaughtered when the glycogen store in its muscles is low, less lactic acid is created and the meat will have a higher pH and darker colour.
Stress can be caused by a number of factors including:
- physical activity (eg mustering, yarding, transporting, loading, unloading)
- emotional stress (eg animal temperament and age, familiarity with handling, mixing/seperation, excessive noise, unfamiliar environments, dehydration, weaning)
- other agents (eg sudden climactic changes especially cold snaps, inappropriate use of hormone growth promotants, oestrus in heifers, disease/parasite status and gender).
The effect of stressors is cumulative so an animal already burdened with one stressor is less able to cope with another. Therefore, it is important that multiple stressors are avoided or minimised.
If stress has occurred, producers should remember that the replacement of glycogen in the muscle is slow. During a recovery period, feed is essential as fasting almost eliminates all glycogen resynthesis and the feed provided should have adequate energy levels for growth. The glycogen resynthesis processes after acute stress can take up to 14 days.
Additional stress during summer
Heat and climatic conditions during summer can add further stress to cattle. Producers should be aware that glycogen levels may be affected in the following ways:
- the first wave of hot weather or unusually prolonged heat waves can cause animals to go off feed, thereby depleting the glycogen bucket
- hot temperatures can cause stress, so consider transporting cattle in the early morning or evening
- summer thunder storms, while inevitable, will be a stressor to animals
- sweating and high respiration rates can cause dehydration which can lead to glycogen loss. Keep curfew times on farm to a minimum and make sure water is available to stock at all times, including before they are transported
- adequate fat cover does not necessarily indicate high muscle glycogen content
- the feed quality at the end of summer needs to be monitored to ensure animals do not lose weight
- acute stress depletes glycogen reserves quickly; if animals have already lost glycogen due to the climatic conditions associated with summer, additional stressors will deplete it further.
To determine critical times of the year for MSA compliance and to allow plenty of time to prepare the glycogen bucket, use the new online feedback system myMSA. The feedback system also allows producers to generate compliance reports over specific time periods.
