Nutrient Regulation of Growth

NUTRIENT REGULATION OF GROWTH OBJECTIVES • Explain nutrient partitioning • Explain Compensatory growth • Explain the purpose of antibacterial feed additives NUTRIENT PARTITIONING • Plane of nutrition – nutritional status of animals • Definition – amount of nutrients consumed by an animal relative to the amount required for optimal growth and or performance • Dietary energy is a major determinant of plane of nutrition • Dependent of the amount of carbohydrate, fat, and protein present in the diet NUTRIENT PARTITIONING • Utilization of ingested nutrient is partitioned among various tissue and organs according to their metabolic rate and physiological importance. NUTRIENT PARTITIONING • The order of priority from highest to lowest • Systems • • • • • Nervous System Circulatory System Respiratory System Digestive System Reproductive System • Tissues • Skeletal • Muscle • Adipose NUTRIENT PARTITIONING ENERGY BALANCE • Positive energy balance – when food is plentiful enough for body maintenance, growth, and fattening • Negative energy balance – food intake is not sufficient to meet needs. • Ex. Dairy cows during peak lactation • Daily milk production is at its highest and dairy cows cannot consume enough feed to maintain body tissue mass. • Energy must be mobilized from body tissues to support production of milk UNDER NUTRITION • Prenatal • Should under nutrition occurs, it is likely to have effect on postnatal growth of animals. • Low birth weights are often a result of prenatal under nutrition RUNT PIGS • Vital organs are smaller and DNA content in various tissues is less • Less DNA in skeletal muscle results in fewer fiber muscles • This results in lean growth being met sooner which negatively impacts the carcass • Slower growth and fatter carcasses UNDER NUTRITION • Postnatal • Increased metabolic activity at birth necessary for maintaining body temperature • Some species use adipose tissue as a source of energy • Large amounts of brown fat may be mobilized for heat production, but livestock species contain little brown fat after birth. • White adipose tissues may be used as energy sources, but in pigs there are only small amounts of fat present. COMPENSATORY GROWTH • Compenstatory growth – growth exhibited by an animal after a period of nutritional stress • Rate of compensatory growth is higher than that exhibited by a genetically identical animal during normal growth COMPENSATORY GROWTH • Two types of compensatory growth • Recovering Weight for Age • Animal is catching up to the normal without requiring additional time • Extended Growth Period • Feed restriction is so severe that the entire growth curve is extended COMPENSATORY GROWTH • Permanent Stunting of Growth- severe nutrient deprivation in postnatal stages of growth commonly results in smaller mature body size and is associated with excessive fat deposition ANTIBACTERIAL FEED ADDITIVES • Ionophores • Commonly fed to cattle because of increased growth efficiency • Alter the cell membrane properties and play a major role in altering microbial populations in the digestive system • Change the population of metabolism of rumen microbes • Can be used as a coccidio stat (anticoccidial drug) • Improves feed conversion ANTIBACTERIAL FEED ADDITIVES • Antibiotics are used in poultry, swine, and cattle feed additives • Theraputic level – Treats sick animals • Prophylactic levels – prevents disease • Subtheraputic levels – in healthy animals it improves feed efficiency and growth rates • Mode of action – changes populations of GI microorganisms, which alters nutrient utilization and metabolism