diet and growth

Question 1

how to measure growth

Answer 1

weight, height (wither height and hip height), bone circumference, bone density, joint quality

Question 2

body weight as a % of mature weight

Answer 2

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

Question 3

effect of protein quality on growth

Answer 3

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

Question 4

effect of calorie height on wither height

Answer 4

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

Question 5

effects of protein intake on wither height

Answer 5

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

Question 6

effect of Ca on wither height

Answer 6

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

Question 7

effect of Ca on bone density

Answer 7

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

Question 8

how does exercise affect bone density?

Answer 8

exercise greatly increases bone density, stall confinement has a negative affect on bone density

Question 9

Bone development

Answer 9

epiphyseal growth plate allows an increase in width, metaphysical growth plate allows the bone to increase in length

Question 10

physitis

Answer 10

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

Question 11

osteochondrosis

Answer 11

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

Question 12

flexural and angular limb deformities

Answer 12

may be present at birth, may improve or worsen with growth, can result in uneven loading of joints (may presdispose to physitis and osteochondrosis)

Question 13

causes of Developmental orthopedic disorder

Answer 13

genetics-some breeds have higher incidence than o thers
conformation-affects loading in joints
management-environment (ex hard ground), housing/exerciseand nutrition

Question 14

Nutrition and developmental orthopedic disease

Answer 14

slow growth followed by rapid growth increases flexural deformities, very rapid growth produces more evidence of developmental orthopedic disease than moderate growth

Question 15

high concentrate diets affect on DOD

Answer 15

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

Question 16

copper and DOD

Answer 16

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

Question 17

DOD and growth rate

Answer 17

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.

Question 18

How to manage growth rate

Answer 18

nutrition is a tool to manage growth rate, extra calories make a horse grow faster

Question 19

effects of protein intake on weight gain

Answer 19

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

Question 20

effect of calorie intake on weight gain

Answer 20

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

Question 21

calories

Answer 21

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

Question 22

how to build a better athlete

Answer 22

moderate, steady growth is more desirable, very rapid/uneven growth is less desirable

Question 23

How to use nutrition to manage growth rate

Answer 23

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

Question 24

sources of nutrients during growth

Answer 24

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

Question 25

growth in the winter and spring

Answer 25

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

Question 26

skeletal growth curve

Answer 26

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