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Environment and Genotype Effects on Pig Growth and Carcass Composition

A trial was conducted using two hundred eighty-eight pigs to evaluate the interactive effects of production system, genetic potential for lean gain, and antibiotic treatment on pig growth rates and carcass composition. Littermate barrows and gilts were either segregated-early-weaned at 13 days of age to an off-site nursery and finisher (EW - 3 site) or conventionally weaned at 26 days of age to an on-site nursery and finisher (Cont. Flow). The genotypes used in this study were

These pigs were fed a diet with or without antibiotics from weaning to market. In the nursery medicated animals received Mecadox® and in the finisher they were given BMD®. All of the diets were calculated to meet or exceed all nutrient requirements.

The results were as follows :

  EW - 3 site Cont. Flow  

 

ETS

YL

ETS

YL

Sig.c

ADG, lb.

 

 

 

 

 

d 0 - 53

.742

.784

.700

.719

E** T***

d 53 - 101a

1.48

1.49

1.40

1.30

E*** S*

d 101 - 142a

1.36

1.29

1.52

1.13

G*** T* GxE**

d 142 - marketa

1.61

1.72

1.80

1.72

S*

ADFI, lb.

 

 

 

 

 

d 0 - 53

.974

1.08

.966

1.036

G** T*

d 53 - 101a

3.07

3.49

2.89

2.92

E*** G*** S** ExG***

d 101 - 142a

3.82

4.09

4.29

3.90

S** ExG**

d 142 - marketa

5.39

6.78

5.58

5.96

E** G*** S*** ExG***

Days to Market

191

190

185

198

S* G*** ExG***

10th Rib BFb, in.

.65

1.03

.67

.88

E** S*** G*** ExG***

LEAb, in2

7.64

6.01

7.31

6.01

S*** G***

Percent Leanb, %

57.5

49.9

56.6

51.4

S*** G*** ExG*

Death loss, %

3.6

2.8

18.5

5.6

E** G* ExG*

a = adjusted for end of nursery weights (d 53 weights).

b = adjusted for slaughter weights.

c = significance levels : * P<.05, ** P<.01, *** P<.001 ; E = environment, G = genotype,

T = treatment, S = sex, ExG = environment by genotype interaction.

This project has shown that there are definite environment by genotype interactions that effect growth performance and carcass composition. The interactions for carcass composition are most evident in the 10th rib backfat measurements. The YL pigs in the EW - 3 site environment were overconsuming energy and depositing this excess energy as fat. This increase in backfat then decreased their percent lean. Subsequently it is becoming increasingly necessary for a producer to match the genotype of the pig to the production system of the farm.


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