Liveweight loss and recovery in cattle
The liveweight of an animal is important as it is often used as the basis for trading live cattle and because it is the major determinant of carcase weight. Considerable financial loss can occur during the short selling period due to liveweight loss.
The liveweight of an animal includes the weight of the body tissues and the contents of the alimentary tract (gut fill) and bladder. Losses in any of these components, including tissue moisture, will reduce liveweight.
The times of day that cattle graze are normally related to sunrise and sunset. This causes a diurnal fluctuation in liveweight and day to day variations throughout the year. Naturally, as soon as cattle are deprived of feed and water they begin to lose liveweight. Indeed, they may already be losing weight, because of the normal fluctuation in liveweight.
Change in gut fill has the greatest influence on liveweight. In adult cattle, gut fill can account for 12–22% of an animal’s liveweight. The main factors that determine the weight of gut fill are the quantity of water drunk, feed quantity and quality, the time since the animal last drank or ate, and the rate of passage of the gut contents. During the selling, water consumption has the greatest effect.
Pasture type and season affect the percentage of gut fill, with fill increasing as feed quality and palatability decline. Cattle that graze on pasture, or are fed roughage, have a higher percentage of their liveweight as gut fill than those on a grain diet, and lose liveweight at a faster rate. Gut fill of cattle on grain diets decreases as the proportion of grain in their diet, and the length of time on grain increase.
Rates of liveweight loss are measured relative to initial liveweight. Cattle lose liveweight most rapidly during the first 12 hours without feed and water, after which the rate of loss slows progressively. This means that much of the total loss in liveweight usually occurs before animals leave the property, particularly if they are mustered well in advance of transporting. If animals are not offered feed and water they will continue to lose liveweight, at a decreasing rate until they eventually die.
The general weight loss pattern to 72 hours is shown in Table 1. The pattern is similar for cattle that have access to water but not to feed.
Table 1. Average liveweight loss up to 72 hours without feed and water for cattle of various liveweights
|Hours without feed and water||Liveweight loss (%)||Estimated liveweight loss (kg)|
On the basis of available data, for cattle without feed and water throughout the selling process, average liveweight losses are approximately 2.5, 4, 6, 10 and 12% of initial liveweight after 6, 12, 24, 48 and 72 hours respectively. However, cattle usually have intermittent access to feed and/or water during the selling process. Liveweight losses have been reported at around 9% after 3 days and 10% after 5 days in unfed animals, but only about 5.5% and 8% respectively, in fed animals. For longer periods with intermittent access to feed and water, losses have been estimated at less than 12% after 8 days and 14% after 10–11 days.
It is recommended that cattle are held off feed and water for six to eight hours before transporting as they travel better, are easier to handle and are cleaner on arrival. Cattle are also deprived of feed and water while they are travelling, so further loss of liveweight is inevitable. Therefore, any unnecessary delays between mustering and selling should be avoided to minimise liveweight loss. Generally, the time factor is more important than the distance cattle travel.
Providing water whenever possible during the selling process is the major key to reducing liveweight loss, while providing hay and/or salt, with water, will further reduce loss.
In Australia, store (non-slaughter) cattle are normally sold either on a per head basis by private negotiation in the paddock, or by auction at saleyards, or on a per kilogram liveweight basis soon after arrival at feedlots.
The effect of the selling process on subsequent weight gain is important to the new owner, such as feedlot operators. The total time of full feed and water during the selling period, rather than the length of any interim fasting period, has the greatest influence on long liveweight recovery.
Available evidence indicates that cattle require 3 to 21 days (generally 10 to 21 days) to recover their initial liveweight after periods of fasting and transportation. This seems to be irrespective of whether they recover in a feedlot or on pasture.
Jennifer Wythes, formerly QLMA Brisbane.