Poultry: Compensatory Growth

Table of Contents

1. What is it?
2. Turkeys
3. Broilers
4. Present Study
5. Experimental
6. Conclusion
7. References

What is it?

Compensatory growth, is referred to as the rapid weight gain that usually follows a period of reduced nutrient intake of an animal, when it is placed back on a high quality diet. Since the animal will be underweight for its age, increased nutrient intake is usually noted leading to a fairly rapid and efficient gain in body weight.

This practice was relatively common with beef cattle where young stock were fed low quality feed, basically, reduced nutrient intake, during the winter and early spring months. With the appearance of lush high quality pasture, the animals were offered a high quality forage leading to a high nutrient intake. This usually resulted in the animals compensating for their small weight gain during the winter months, with an enhanced feed efficiency.

Poultry Research

Turkeys

In the early 70's English workers looked at using compensatory growth to enhance the efficiency of growing heavy weight turkeys. Their reports, Auckland et al (1969), and Auckland and Morris (1971 a&b), showed that reduced body weight of turkeys up to 6 weeks of age, from the feeding of low protein diets, resulted in weight gain equal to the controls at market age, but with a significant improvement in feed:gain ratio and an overall reduction in protein intake. Leeson and Summers (1978), with investigating compensatory growth, also looked at diet self selection for turkeys. They found that birds given the choice to select a high energy low protein diet, or a high protein low energy diet, had similar body weights to that of control birds at market age but with an improved feed:gain ratio and more carcass protein. Plavnik and Hurwitz (1991) looked at restricting feed with turkeys, starting at 7 days of age for a 10 day period. At 20 weeks of age they noted better body weight, feed utilization and meat yield for the early feed resticted birds as compared to the contols. For some reason the compensatory gain program has received only passing interest from the turkey industry.

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Broilers

Both the beef cow and the turkey have feeding periods extending into months, as compared to the chicken broiler which has only a relatively short growing period. Therefore, it would be expected that broilers on a compensatory growth program might have problems achieving similar weights at market age as compared to birds reared on a regular feeding program. Several metabolic disorders such as various leg problems, sudden death syndrome and ascites, were thought to be enhanced by the rapid early growth of the modern day broiler. Thus, studies were done to look at the possibility of slowing down growth at an early age, to see what effect this would have on these problems. A number of studies were reported from several areas around the world, all indicating that slowing weight gain of broilers down during the second week of life, often resulted in a significant reduction in mortality from the above mentioned conditions. However, in most but not all cases, a slight reduction in body weight and enhanced fat deposition was noted at market age.

In the 80's Israeli workers,(Plavnik and Hurwitz 1985, 1988) investigated the possibility of utilizing a compensatory growth program to improve the feed utilization of market weight broilers. Their program resulted in restricting feed during the 3 to 14 day period for 7 days, at a level of 1.5 kcal/g body weight^0.67. This level of feed intake was considered to just meet maintenance requirements, and so, little or no gain in body weight was anticipated. While the program did achieve enhanced feed utilization, in some cases, body weight of the compensatory birds did not equal that of the control group at market age. Also an increase in the carcass fat content of the test birds was often noted.

In the early 90's Dr. Leeson's lab at Guelph, also began looking at the possibility of improving feed:gain ratio of broilers by restricting nutrient intake at an early age, so that the growth curve of the bird was more concave in nature rather than linear. As pointed out by Zubair and Leeson (1994), the improvement in feed efficiency noted with compensatory growth was due to the smaller body mass of the bird up to the point of growth compensation. Thus a lower nutrient requirement for maintenance.

Present Study

Since achieving identical body weight for age, with similar meat yield, is necessary if the compensatory growth program is to be accepted by the industry, a further study was undertaken by workers at the University of Guelph (Lee and Leeson, 2001). A short summary of their findings is as follows.

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Experimental

Male broilers were used in 3 experiments where birds were subjected to various levels of feed restriction starting as early as 4 days of age, and varying in duration. Also a further approach to reducing early nutrient intake was to feed the starter diet, diluted 50% with oat hulls, for various lengths of time. Feed restriction was calculated so that nutrient intake varied per kg body weight in an attempt to just meet the maintenance requirement of the birds during the restriction period, thus minimizing weight gain.

Confirming previous work reported, there was no consistent response with broilers in the present study with regard to growth compensation. Birds in experiment 1 resulted in complete compensation, while several treatments in experiments 2 and 3 did not. However, in all experiments a significant improvement was made in feed:gain ratio. Little or no difference was noted in carcass characteristics for the compensatory versus birds grown on a normal feeding program.

Conclusion

The authors conclude from their study that a period of moderate nutrient restriction amounting to 0.75 to 1.50 kcal ME/gBW^0.67, for 3 to 4 days, during the second week of growth, appears ideal in terms of subsequent growth and feed utilization.

Feed restriction and the use of diluted diets may not be easy to implement at the farm level. Physical feed restriction requires daily weighing of feed and an even more difficult challenge is ensuring equal distribution of this limited feed. The alternative approach of diluting the diet with products such as oat hulls for 7 to 9 days, while often achieving results similar to that of the feed restriction approach, there appears to be more of a chance that weight gains will not equal that of birds fed on a regular feeding program at market age. Also the nutrient cost of a such a diet is greater.

As the authors point out, the potential benefits in feed savings and hence economical returns with the compensatory growth program, warrants serious consideration by the industry. The improvement in feed:gain ratio noted in experiment 1 of the present study, was .13 (average of the 3 test diets of 1.84 vs. 1.97 for the control fed birds). This would amount to a feed saving of 3640 kg for a 10,000 bird flock using the average weight of 2800 g/bird (6.17 lb.) obtained in the present study. Such a potential economical return should be incentive for more research to be conducted in this area.

References

Auckland J.N., T.R. Morris and R.C. Jennings, 1969. comensatory growth after under nutrition in market turkeys. British Poultry Sci. 10:293-302.

Auckland J.N., and T.R. Morris, 1971(a). Compensatory growth in turkeys: effect of under nutrition on subsequent requirements. British Poultry Sci. 12:41-48.

Auckland J.N., and T.R. Morris, 1971(b). Compensatory growth after under nutrition in market turkeys: effect of low protein feeding and realimentation on body composition.

Lee K.H., and S. Leeson, 2001. Performance of broilers fed limited quantities of feed or nutrients during seven to fourteen days of age. Poultry Sci.80:446-454.

Leeson S., and J.D. Summers, 1978. Dietary self selection by turkeys. Poultry Sci. 57:1579-1585.

Plavnik I., and S. Hurwitz, 1985. The performance of broiler chicks during and following a severe feed resriction at an early age. Poultry Sci. 64: 348-355

Plavnik I., and S. Hurwitz 1991. Response of broiler chicks and turkey poults to feed restriction of varied severity during early life. British Poultry Sci. 32:343-352.

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