Growth and Development – Composition An S 426 Spring 2007

Growth and Development – Composition Function of genotype and environment Function of genotype and environment –Cattle have 30 pairs of chromosomes Sex determines the development and function of the organs and glands Sex determines the development and function of the organs and glandsExample: Glands produce hormones which cause certain Glands produce hormones which cause certain things to occur in the body – some seen and others unseenExamples:

Growth and Development – Composition Sigmoid prenatal and postnatal growth patterns

Growth and Development – Composition Four segments of growth curve (i.e. postnatal) Four segments of growth curve (i.e. postnatal) Compensatory gain Compensatory gain Why important:

Impacts of frame size – LargeSmall ItemImplant No implant Implant 1-64 day (Period 1) Initial wt, lb End wt, lb DFI, lb DM ADG, lb F/G, lb (+0.7%) (+20.7%) 5.98 (+18.3%) day (Period 2) End wt, lb DFI, lb DM ADG, lb F/G, lb (+5.6%) (+16.2%) (+7.8%)

Impacts of frame size – LargeSmall ItemImplant No implant Implant day (Period 3) End wt, lb DFI, lb DM ADG, lb F/G, lb (+12.5%) 9.08(+ 3.1%)

Impacts of frame size – LargeSmall ItemImplant No implant Implant Total feeding period End wt, lb End wt, lb DFI, lb DM DFI, lb DM ADG, lb ADG, lb F/G, lb F/G, lbDP BF, in LEA, sq in QG QG (+6.2%) C C (+18.8%) 7.63 (+13.3%) C C

Growth and Development – Composition Results: Results: 1. Later maturity of large framed cattle Period 1 – no difference between types for ADG and F/G Period 2 – small framed cattle gained slower and were less efficient Period 3 – large framed cattle became less efficient 2. Large type cattle had higher DFI and ADG (P < 0.01) –F/G over total feeding period nearly the same

Growth and Development – Composition Results: Results: 3.Implants improved ADG (P < 0.01); 44 lb. in large and 70 lb in small framed cattle –F/G was improved % in small type cattle, but no difference in large type cattle

Growth and Development – Composition Results: Results: 4.Large frame cattle had less BF and larger LEA; when adjusted for carcass weight, small type had larger LEA (P < 0.01) 5.Small framed cattle appear to respond more to implants than large framed cattle

Growth and Development – Composition Endocrinology – Endocrinology – Interrelationships of small, medium and large frame cattle and estradiol implants Study:Assumptions:1.2.

Growth and Development – Composition TreatmentInsulin Growth hormone mg / ml Small Implant No implant No implant Medium Implant No implant No implant1.85 (1.96) (1.96) (1.34) (1.34) (2.8) (2.8) (3.1) (3.1)2.5

Growth and Development – Composition TreatmentInsulin Growth hormone mg / ml Large Implant No implant No implant All cattle Implant No implant No implant1.43(1.23) (5.4)

Growth and Development – Composition Results: Results: 1.Small frame, earlier maturing cattle, had higher concentrations of insulin (P < 0.05) and lower concentrations of GH 2.Large frame, later maturing cattle, had higher concentrations of GH (P < 0.10) and lower concentrations of insulin 3.Within each cattle type, implanted cattle had higher concentrations of GH

Growth and Development – Composition Results: Results: 4.Thus, higher insulin concentrations in small, early maturity types of cattle may explain earlier fat deposition Whereas, the greater concentrations of GH in large, later maturing types of cattle may account for the greater growth rate and later fat deposition

Growth and Development – Composition Concepts of growth and development Concepts of growth and development –Deposition of tissues: 1 st 2 nd 3 rd 4 th

Growth and Development – Composition Concepts of growth and development Concepts of growth and development –Muscle and fat development Number of cells determined early in prenatal period To increase muscle, need to select for more cells To increase muscle, need to select for more cells To increase fat, increase fat cell size To increase fat, increase fat cell size fat distribution in carcass: –Subcutaneous = –Intermuscular = –Intramuscular = –Internal =

Growth and Development – Composition Concepts of growth and development Concepts of growth and development –Schematic:

Growth and Development – Composition Concepts of growth and development Concepts of growth and development GHRF – Synthetic estrogens (implants)