What is ADG?
Average daily gain (ADG) is a performance measure that many beef cattle producers monitor. Average daily gain is simply the rate of weight gain per day over a specified period of time. For example, if a calf weighs 600 pounds on June 1 and later weighs 750 pounds on July 31 of that same year, then it gained 150 pounds in 60 days. Divide 150 pounds by 60 days, and the ADG comes out to be 2.5 pounds per day.
What affects ADG?
Average daily gain is affected by many factors. The animal’s diet (including forages, grain-based supplements, mineral and vitamin supplements, and feed additives) is important in determining ADG. Whether or not cattle have received growth-promoting implants or are fed ionophores may notably affect ADG. These technologies are designed to boost ADG on existing diets. For implants to be effective, however, a minimum ADG of around 1.3 pounds per day is needed.
Genetics plays a key role in determining ADG. Continental breeds of cattle generally gain weight more rapidly than other breed groups. Within breeds, expected progeny differences are based on individual genetics and predict growth rate differences among individual cattle. Crossbreeding can be used to capitalize on heterosis (where the calf performs better than the average of its parents) and enhance ADG. The influence of genetics on ADG does not stop there. Cattle genetics and environment interact to affect performance traits such as ADG. Even before a calf is born, the maternal environment and diet affect embryonic and fetal development in such a way that the lifetime performance of the calf-to-be is impacted. So, post-weaning ADG is affected in the womb among other factors.
Why does ADG vary so much?
A wide range of ADG values occur on beef cattle operations. Cows losing body condition and weight after calving have negative ADG for a period of time. Cattle that neither gain nor lose weight have an ADG of zero. These cattle are maintaining their body weight. Positive ADG values indicate that cattle are gaining weight. Throughout the production cycle, mature cattle may experience periods of positive, neutral, and negative ADG. Growing cattle, on the other hand, should consistently gain weight and have positive ADG. Furthermore, minimum ADG thresholds are typically desired for growing cattle, though these targets may change as the calf ages.
Performance targets for ADG must consider production conditions. Declines in the quality of late summer grazing on warm-season perennial pastures often lead to lower ADG during that time of year as compared with grazing earlier in the season when more vegetative forage is available. In addition, the effects of heat stress on cattle are often more profound in August than in May potentially affecting forage intake, cattle nutrient needs, and ADG. Likewise, extended periods of cold, wet weather may decrease ADG if management changes are not implemented to offset these potential lesser gains.