Several factors impact shrink including transit time, transit distance, environmental conditions (weather and transit conditions), cattle handling methods, and cattle management including nutrition. Research indicates that the combined effects of shipping and handling result in greater weight loss than holding cattle off of feed and water alone. Transit shrink in beef steers has been demonstrated to represent as much as 68% of the shrink from the combination of both fasting and transport. Weight loss varies depending on the circumstances, but a good rule of thumb estimate is that about 0.75% of cattle body weight will be lost per day with feed and water deprivation, and the weight loss will not necessarily be the same amount each day. When feed and water are unavailable, study results indicate that cattle shrink about 1% per hour for the first three to four hours and then roughly 0.25% per hour for the next eight to ten hours. This weight loss can increase several-fold when transport stress is added.
A Florida study reported that newly weaned beef calves that were transported three hours lost 5.3% of their body weight after transport and averaged a body weight loss of 3.4% after one week, while similar newly weaned calves that were not transported increased their body weight by 0.7% over the same seven-day period. In a second trial, however, the transported calves regained lost body weight faster than non-transported calves over a 2-week period. Other research from Texas and Oklahoma indicates that transportation shrink varies more from year to year than from preweaning management, suggesting that climatic conditions may be a major factor affecting body weight losses of transported beef calves. Another study found that steers transported five hours lost 4.6% of their body weight, steers transported ten hours lost 6.5% of their body weight, and steers transported fifteen hours lost 7.0% of their body weight illustrating that increased transit time tends to increase shrink. In this trial, recovery to pre-transit weights took five days. This is normally the minimum recovery time. Recovery can take up to 30 days in more severe situations. It is generally accepted that increasing transit time exacerbates feed and water deprivation and leads to dehydration. Emphasizing low stress cattle handling and shipping in minimum time can benefit both buyer and seller by reducing cattle shrink, stress, morbidity, and cost to regain lost weight.
The amount of fill can affect the degree of shrink. Lush grass, silage, and haylage diets usually produce more gut fill than hay or high-concentrate diets. Cattle shipped directly off of milk and grass may undergo a greater percentage shrink than cattle off of a preconditioning or hay and grain diet. In addition, calves shipped directly off of their dams must deal with weaning stress and possible unfamiliarity with feed bunks and water troughs. Many producers attribute shrink to loss of gut fill alone. Much of this weight loss is gut fill, feces, and urine that can be easily replaced. However, some of this weight loss is actual loss of body tissue. Research out of Oklahoma showed that fecal losses accounted for 65% of total body weight lost, and urinary excretions accounted for 38% of the weight lost. This leaves 7% weight loss from another source, likely body tissues (carcass components). Tissue loss takes longer to regain than weight loss from urine and feces. Since muscle contains more water than fat, higher levels of shrink are typically encountered in cattle with higher lean to fat ratios. Therefore, cattle frame size, age, sex, and body condition can impact degree of shrink.
Management strategies that have been researched in an attempt to deal with transport stress and reduce shrink have included preconditioning programs, rest periods during and after transit, potassium supplementation, and use of electrolyte solutions. Research shows that transported or feed and water deprived cattle are challenged with a mild metabolic acidosis which may be the result of body water loss. There is evidence that either electrolyte solutions or water can help alleviate this dehydration and some stress in transported cattle. Any added stress such as overloading the truck, unfamiliarity with confinement, or extreme temperature and moisture conditions can increase shrink. Cattle with temperament problems may be subject to higher levels of shrink as well. There is new evidence from Florida and North Carolina that early-weaned calves maintained onsite before shipping might be more tolerant of the stressors associated with transportation and feedlot entry. Although this research revealed no difference in shrink, there was a notable difference in recovery of lost weight, with early-weaned and preconditioned calves having an advantage over traditionally weaned calves.
Source: Mississippi State Unviersity