Abstract
Simple SummaryAnimal production is focused on maximizing profits with simultaneous animal welfare protection. Thus, discovery of a simple, stress-free method for gilt selection would be an indispensable element for production improvement and would give necessary knowledge for producers. Our data showed that vagina–cervix length measurements could be a good, additional tool to predict a sow’s likely future reproduction efficiency. The advantages for this method are simplicity, speed, and no cost; the measurement is made as an element of the standard insemination procedure without additional stress and in a relatively early stage of life. Consequently, immediately obtained information gives high reliability and effectiveness in gilt selection. The length of the distal part of the internal reproductive tract seems to be related to the length and capacity of uterine horns, which is the most important anatomical property influencing litter size in sows. The aim of this study was to evaluate variation in vagina–cervix length (VCL) in gilts and differences in reproductive performance of sows according to VCL. The study was performed in a commercial farm using 221 gilts introduced into the breeding herd. Females were divided into three groups: (S) short (26.0 ± 2.0 cm, n = 36), (M) medium (31.3 ± 1.46 cm; n = 121), and (L) long VCL (36.0 ± 1.4 cm; n = 42) (p < 0.01). Mean live weight of gilts did not differ significantly among groups. Mean first litter size significantly varied between groups S (10.47 ± 3.01) and L (11.98 ± 2.32) (p = 0.0075) and M (10.67 ± 2.98) and L (p = 0.0054), while there was no significant difference between group S and M. Significant advantage (p = 0.023) was noted in the number of litters obtained from sows in groups L (4.69 ± 3.14), M (3.67 ± 2.71), and S (3.36 ± 2.40), and thus in total life production of sows (p = 0.0054), i.e., the number of piglets born alive. To conclude, the differences in vagina–cervix length in gilts during the first service was associated with significant variability in litter size during the first reproductive cycle, giving an advantage to females with longer VCL. Gilts with longer VCL were culled later and gave significantly more litters. Consequently, their lifetime piglet production was greater than gilts with shorter VCL.
Highlights
An important factor for economic efficiency in pig production is the reproductive potential of sows, litter size [1]
The aim of the current study is to evaluate differentiation in VCL in gilts during the second estrus, as measured by a catheter during insemination, and differences in lifetime reproductive performance of sows according to different vagina–cervix length
The mean VCL differed significantly (p < 0.01) among specified groups of gilts, there were no significant differences in mean body weight (Table 1)
Summary
An important factor for economic efficiency in pig production is the reproductive potential of sows, litter size [1]. Unilateral selection for ovulation rate gives a good response due to the number of CL, but has only minor effects on litter size in pigs [5]. Selection of gilts for uterine capacity as the second physiological reproductive coefficient could be effective in terms of the increase in litter size, there is no simple method to evaluate it. The model of selection for litter size as a single feature is performed in most of breeding programs. The effects of such selection, better than selection for ovulation rate only, are still unsatisfactory. Performance test evaluation of the uterine capacity in gilts and sows is impossible to perform as a direct assessment. VCL is highly correlated to the length of the uterine horns: a 1 cm longer
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