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Physiological characteristics of late puberty gilts administered P.G. 600
The objective was to determine the effect of P.G. 600 in gilts that did not show estrus in response to boar exposure at 180 d of age. Landrace × Large White composite gilts (n=217) were housed in groups of 15 pigs per pen (0.84 m2). Starting at 181 d of age, gilts were checked daily for estrus. After 29 d of boar exposure, gilts were classified as either early puberty (EP; n=45) or randomly assigned to non-pubertal control (CON; n=40) or non-pubertal P.G. 600 (PG; n=40). Gilts in the PG group were administered 5 cc of P.G. 600. At 240 d of age all gilts were eligible to be bred for 30 d. Reproductive tracts (RT) from non-cyclic gilts and weaned sows were obtained from an abattoir. Data was analyzed in SAS using PROC MIXED. Fixed effects for RT traits included treatment group, puberty status, parity and a covariate of harvest weight. Average daily gain was greater (p<0.01) for EP than PG or CON (740 vs. 670 and 670g, respectively). The proportion of PG and CON gilts that obtained puberty was 70% and 65%, respectively. Days to estrus after boar exposure for EP, PG, and CON differed (p<0.01, 9.6, 40.0, and 46.8 d, respectively). Group means for RT traits are reported in Table 1. In general, RT of the PG group were comparable to CON. Early puberty females exhibited increased reproductive tract development compared with PG and CON. Ovarian characteristics were similar among the left ovaries of EP, PG, and CON females. However, weight and ovulation rate were greater (p
<0.05) for the right ovary of EP females compared with their PG and CON counterparts. Results indicate that P.G. 600 had little impact on reproductive tract development in gilts that did not respond to boar exposure at 180 d of age.
Table 1.
|
Experimental Group |
|
||
RT trait |
EG |
PG |
CON |
P-value |
Total wt, g |
984b |
791a |
830a |
0.02 |
Uterus wt, g |
666a |
481b |
549ab |
0.02 |
Vulva wt, g |
130b |
112a |
111a |
0.02 |
Left ovary |
|
|
|
|
Wt, g |
9.0 |
8.1 |
7.7 |
0.56 |
Width, mm |
36.4a |
32.5b |
33.9ab |
0.08 |
Corpora lutea |
7.1 |
6.1 |
5.1 |
0.32 |
Corpora albicantia |
6.8b |
7.1b |
4.4a |
0.08 |
Right ovary |
|
|
|
|
Wt, g |
9.5b |
6.4a |
7.0a |
<0.01 |
Width, mm |
35.8a |
30.7b |
33.3ab |
0.01 |
Corpora lutea |
7.4b |
3.7a |
4.2a |
<0.01 |
Corpora albicantia |
6.7ab |
7.2b |
4.6a |
0.08 |
Means with different superscripts differ (p<0.05).
Keywords: Estrus, Gilt, PG600