WHOLE BODY ANIMAL GROWTH

ANSC 590 ANIMAL GROWTH AND DEVELOPMENT

GROWTH CURVES

Represents an increase in size relative to a period of time (figure 9.1)

Often impacted on compositional levels of varying tissues ie. Muscle, fat, bone, CT

Dependent on plane of nutrition and stage of development

Four phases of growth (figure 9.5)

AGE and MATURITY

Chronological versus physiological Maturity is the point in time when an

animal reaches its highest level of complexity or development

Absolute growth rate: utilizes unitsADG, WDA, Birth, Weaning, etc. (Figure 9.9)Growth rates of various tissues (figure 9.11)

Changes in Body Measurements

Quantifiable Carcass length in pork – value

Standard reference points of measurement LEA/REA (LD muscle)- cross section FT (SubQ) – where is the best place to

measure????? Body weight measures (table 9.2)

Body Measures

Empty body wt.Withhold feed and water for 24 hours prior to

slaughter to secure shrunken weightsResearch methods: withhold feed for 12-24

hrs. prior to weighing if conducting research Pasture gain test

Conduct a pre and post weight (shrunk wt. if less than 90 day trial)

Dressing percent

Removal of everything but the carcass Factors that affect DP: fill, muscle, fat,

hide, etc. Assessment of value in the animal industry

Table 9.3

Changes in carcass components

Figures (9.13,14,15) Bone- increases at a decreasing rate Muscle is the fastest growing during early life

and post weaning, yet decreases with time Fat is the fastest growing at physiological

maturity A decrease in bone and muscle is due to the

extreme increase in fat percentage

Changes in chemical composition

Protein, fat, and water Muscle ranges from 68-85% Moisture to protein ratio = 4:1 Decreases with age Table 9.4

Myoglobin increases with age Water content of CT and adipose tissue also

decrease with age Water also decreases in bone with age because of

inorganic salts deposited in modified CT to increase bone strength

Changes in chemical composition

CT increases with age Accretion of collagen and elastin fibers must be

increased to form the matrix of fasciluli to form the CT to hold the muscle bundles

Muscle fibers increase in size, yet CT decreases in percent thus increases in size The relative amount of CT in bone and fat is also

affected by the deposition of inorganic salts and lipids

Changes in chemical composition

Nucleoproteins Increases with age yet decreases in %

Fat More variable yet increases or accumulates in various

depots with age including the depots associated with muscle

Minerals Increases with age as a general rule, yet is not true

for some ie. sodium decreases with muscle growth Ca, P, and K all increase with growth and with age

Factors affecting carcass composition Genetics Species Selection and domestication Muscle distribution Fat distribution Breed Frame size Sex

Genetics on carcass composition

Mutation or intensive selection Influence of environment Phenotype versus genotype Heritability estimates Table 9.8

Species affect on carcass composition Variation between species Table 9.9 Deposition of tissues, esp. fat Order of fat deposition between species Proportion of composition compared

anatomically Value differences among composition

parts of each species

Muscle distribution

Table 9.12 & 13 Comparison of muscle wt. distribution between

species Ruminant versus non-ruminant and their

relationship to prehension properties Domestic versus non-domesticated species Meat versus milk type selection Figure 9.26 muscle to bone ratios

Fat distribution

Table 9.14 and Figure 9.19 Huge differences between ruminant and non-

ruminants At the beginning, carcass fat is fairly even in

distribution However, a growth increases and maturity

develops fat begins to accumulate varying percentages at different anatomical locations Figure 9.20 & 27

Breed variations

Various breeds have:Different maturity patternsFrame sizesMeat versus dairy typeSelection pressure for musclingFigure 9.22Table 9.20

Frame Size

Growth patterns Feedlot gain and efficiency Chronological vs Physiological maturity Quality Grade vs fat deposition Compositional Endpoints Dairy vs Meat type Dressing Percentage variations Forage availability and utilization Figures 9.23, 24, & 25 Tables 9.16 - 19

Sex

Definitions Figure 9.28, 29 Table 9.25, 26 Except for pigs, females mature earliest Intact males have a greater proportion of muscles in the

forequarter while heifers in the proximal pelvic limb Castrate males are intermediate Heifers at the same physiological slaughter age and

maturity will be fatter lower yielding