Liveweight Loss & Shrink
Brett Littler, Livestock Officer
Changes in gut fill and bladder fullness have the greatest influence on liveweight in beef cattle. In grown cattle, gut fill and bladder fullness accounts for 12-22% of an animal's liveweight.
The Liveweight loss/Shrink that occurs when we take cattle off feed is something that I spend a lot of time explaining to producers. It is also something that can have a huge effect on what producers think their cattle are doing and how they think they are performing. Unfortunately, sometimes the cattle scales are lying! Also, when you send cattle away for sale, the amount of gut fill that is retained can have a huge influence on the price you receive and also sometimes the performance of your cattle in a feedlot.
There are a number of factors that affect gut fill and the weight of the gut fill. These are the quantity of water drunk, the feed eaten (both quantity and quality), the type of feed (grain, crop or pasture) and also the time since the stock last eaten or drunk anything.Below is a guide as to the percentage liveweight loss when cattle are taken off feed and water.
|Time of feed||% liveweight loss|
In a practical situation, we find the biggest loss of liveweight is when cattle are on very high quality pasture or crops. This is all to do with the rate of passage of the feed and also the high moisture content of the feed. For example, we would expect cattle off an actively growing winter cereal crop will lose 10-14% of their liveweight in the first 16 hours off feed and water. On the other hand, cattle which are on a feedlot diet high in grain will only lose between 3-4% of their liveweight in this same 16 hour period because the smaller overall quantity and weight that they are eating and also its lower moisture content.
Anything that has an effect on the rate of passage through the gut will have an effect on the liveweight. So the type of plant (legumes for the same quality will move through the gut quicker than grass), stage of growth and therefore the digestibility will affect liveweight.
Producers get confused about what is the liveweight loss and think that it is the carcase that is being affected. We know with most cattle (excluding calves 3 months or younger), that it is about 48 hours before we see the carcase starting to be effected and decreasing in weight (starting to dehydrate) and this is why all transport standards are based on allowing stock 48 hours off feed and water. Another thing to consider is that transporting stock is a great laxative and even a relatively short trip will decrease liveweight loss by around 2%.
If you are going to send cattle to sale, think before they go "What have they been eating?" and "What can I give them?" to limit the loss of gut fill and therefore maintain their liveweight and therefore the dollars that you get back in return. Practical experience has shown that pasture hay (don't feed a legume hay) fed out to stock prior to transport to sale can decrease liveweight loss. I would recommend giving it to the cattle prior to them going and ensuring that it is good enough quality that they eat it but not too good as we want it to stay with them.
Finally, a practical example from a producer I have been working with. He gives out pasture hay the day before stock leave his property and he feeds them up to just prior to going on the truck. In the past, he would lose 7-9% of the animals' liveweight. The most recent load that he sent, lost just 3.7%. Interestingly he has found that since he has started feeding hay prior to transport, his sickness/pull rate in the feedlot has dropped and his average daily gain has remained the same.
For more information
Brett Littler, Livestock Officer, Central Tablelands LLS
Phone: 0427 007 398