diet and growth Flashcards
how to measure growth
weight, height (wither height and hip height), bone circumference, bone density, joint quality
body weight as a % of mature weight
approx. 10% of mature weight when born, rate of gain flattens out around 18 months of age and foal is about 50% of mature body weight at 8 months of age
effect of protein quality on growth
low protein quality reduced growth rate, but feeding high CP does not necessarily increase growth. according to one study, 0.3% lys diet resulted in a 0.5 kg Average daily gain and a 0.65% lys diet resulted in a 0.91 kg average daily gain. other studies have shown that feeding high CP diets does not increase growth above adequate diets
effect of calorie height on wither height
study shows weanlings/yearlings fed a diet of either 100% or 150% of their DE requirement did not have any difference in skeletal height. the horses that ate more did not increase height, but did increase weight gain
effects of protein intake on wither height
weanlings/yearlings (8-13 mo old) fed either an 11% CP diet or 13% CP with similar calorie intakes did not affect change in wither height
effect of Ca on wither height
horses 4-12 mo of age, fed either 100% of Ca requirement or 35% of Ca requirement had no significant height change. Horses fed 100% Ca requirement or 50% ca requirement had no significant height differences
effect of Ca on bone density
horses 4 mo-12 mo old fed either 100% of Ca requirement or 35% of Ca requirement. Lower Ca intake had significantly less bone density. Horses fed 100% of Ca requirement or 500% had no difference in bone density
how does exercise affect bone density?
exercise greatly increases bone density, stall confinement has a negative affect on bone density
Bone development
epiphyseal growth plate allows an increase in width, metaphysical growth plate allows the bone to increase in length
physitis
developmental orthopedic disease, inflammation /bone proliferation around the physics (usually at mataphyseal growth plate), most common locations are the fetlock (foals and weanlings) and knee (weanlings and yearlings), often resolves with no long term effects , if severe it can cause lameness and uneven loading and can make angular deformities worse
osteochondrosis
developmental orthopedic disease, defect in normal conversion of cartilage to bone at growth plate, most defects are initiated before one year of age, some early lesions may resolve, can lead to lameness depending on the site and severity, type of horse activity
flexural and angular limb deformities
may be present at birth, may improve or worsen with growth, can result in uneven loading of joints (may presdispose to physitis and osteochondrosis)
causes of Developmental orthopedic disorder
genetics-some breeds have higher incidence than o thers
conformation-affects loading in joints
management-environment (ex hard ground), housing/exerciseand nutrition
Nutrition and developmental orthopedic disease
slow growth followed by rapid growth increases flexural deformities, very rapid growth produces more evidence of developmental orthopedic disease than moderate growth
high concentrate diets affect on DOD
high concentrate diets raise insulin and glucose, affect regulation of endochondral ossification (one small study, no cause and effect). there have been many studies done on effects of “sugar and starch” concentrate vs “fat and fiber”, different diets produce different glucose and insulin responses, has not been shown there is a cause and effect link with a sugar ans starch diet
copper and DOD
low dietary copper affects cartilage development (large survey study followed by several controlled experiments), very low dietary copper does affect cartilage development, but lesions are not exactly the same as DOD, elevated copper did not eliminate the lesions, most diets/feeds today contain adequate amounts of copper so risk of DOD from low Cu is not great
DOD and growth rate
recent studies have shown a link between growth rate and incidence of DOD, faster growing/larger/heavier horses have increased risk so growth rate is important.
How to manage growth rate
nutrition is a tool to manage growth rate, extra calories make a horse grow faster
effects of protein intake on weight gain
weanlings/yearlings 8-13 mo old fed either 11% CP or 13% CP with similar calorie intakes and body weight was measured, there was not a significant difference in average daily gain
effect of calorie intake on weight gain
weanlings and yearlings 130-370 days old werer fed either 100% of DE requirements or 150% of DE requirements. the increase in calories increased the average daily gain
calories
calories are the most important factor in controlling growth rate. high calorie intake=high rate of growth, protein and amino acid intake can limit growth but is not the cause of rapid growth in most cases
how to build a better athlete
moderate, steady growth is more desirable, very rapid/uneven growth is less desirable
How to use nutrition to manage growth rate
growth may become uneven at weaning or during season changes, growth can get irregular after 2 months of age so supplemental feeding may be necessary, to achieve moderate, even growth concentrate feeding programs should be adjusted based on forage quantity and quality
sources of nutrients during growth
milk-birth to weaning
forage (pasture/hay) and concentrate-used before and after weaning, may be used to smooth the weaning transition to even growth rate
growth in the winter and spring
growth is slower in the winter-hay instead of pasture as a forage source and cold weather is a factor
growth speeds up in the spring-mild climate and pasture quality and quantity increase, may result in physitis and flexural deformities
diet should be adjusted to maintain moderate growth in the winter and moderate growth in the spring
skeletal growth curve
0-20 months=rapid change in height
20-40 months=slower growth, but increased density and width
40-60 months=minimal change in height but can change density
