Feed Intake of Growing Pigs: What Can Be Done About It?

Nutrition Update
Volume 10 No.3, February 2000

Improvements in the genetic potential for the modern commercial pig have led to an increased potential for protein deposition. However, up to 30% of this potential is not realized on-farm. Many factors, such as poor housing and management, a failure to provide nutritionally for the needs of the animal and most importantly disease stressors, are responsible for observed performance at levels lower than expected. An animal's voluntary intake will determine its nutrient intake and can have a significant impact on pork production efficiency. Aside from hyperalimentation, which will allow for increased intake but is not a practical solution, what are we to do?

Many stressors affect voluntary intake in pigs. It is well known that cold temperatures can increase intake. The effects of social stress are less well understood. Within a pen, a pig needs a place to eat, a place to drink, a place to eliminate and place to rest. Within the industry, group size in pens is increasing. Conventional thinking has been that as group size goes up, the rate of gain goes down. Recently, it has been suggested that groups of up to 80 grower-finishers in a pen did not have detrimental effects on productivity. Thus the ideas regarding group size for grower-finishers are being re-examined. Activation of the immune system, due to disease conditions, is probably the greatest contributor to a pig not realizing its growth potential. Depending on the extent of the disease stress, simply increasing the nutrient levels, such as lysine or extra vitamins, may not alleviate the problem and will be an increased financial burden on the producer. To date, when there are disease issues, the industry has been quick to offer an antimicrobial product to overcome the loss of performance. However, as routine use of antimicrobial products is placed under increasing scrutiny, alternative strategies such as the use of enzymes and diet acidification will become more common in pig nutrition.

What about variation in feed ingredients? Do different batches of the same ingredient have same feeding value for pigs? Studies with poultry have shown that the environment can have a large impact on the apparent metabolisable energy of wheat. There is not a lot of information about this topic with regard to pigs. Some work has been completed using sorghum that indicates that there can be significant genotype and environmental differences among varieties of an ingredient. A recent review (van Barneveld, 1999) indicated that there are significant differences in energy content of different wheat and barley cultivars. There is a need to define the variations in available energy and amino acid content of ingredients and to understand what factors influence nutritive value.

Thus, understanding feed intake of pigs is quite complex. It is more than just matching the diet to the growth stage of the animal. Many influences, especially immunological challenges, can affect the ability of a pig to express its full genetic potential. It is important to obtain as much information as possible regarding the animal, its environment, potential stressors and the feed ingredients to optimize pig production.

Reference: van Barneveld, R. J. 1999. Chemical and physical characteristics of grains related to variability in energy and amino acid availability in pigs: a review. Aust. J. Agric. Res. 50:667-87.

Prepared by: Ian R. Seddon, Ph.D.

Contact:	David Hunt or Ron Bazylo
	Farm Production Extension Specialist - Swine
	Livestock Knowledge Centre
	Manitoba Agriculture, Food and Rural Initiatives