Semen Characteristics, Testicular Size, and Reproductive Hormone Concentrations in Mature Duroc, Meishan, Fengjing, and Minzhu Boars1

Abstract

Chinese breeds of swine are known for their reproductive prolificacy and are noted for large litter size. The current investigation evaluated reproductive components of three breeds of Chinese boars in comparison to a contemporary site breed common in the U.S. Semen from postpubertal Duroc, Meishan, Fengjing, and Minzhu boars was collected during four seasons of the year. After each semen collection and evaluation period, boars were weighted and placed in a restraining chute for testicular measurements and blood sampling for measurement of FSH, testosterone, and inhibin. Although Duroc boars were 2 mo younger than Chinese boars, initial and final body weight and paired testis volume in Durocs were greater (p < 0.05) than in Chinese boars. Total spermatozoa per ejaculate was similar for Duroc and Minzhu boars, but was lower (p < 0.05) in Fengjing and Meishan boars. Progressive motility and sperm morphological characteristics were not affected by breed of boar. Serum FSH concentrations were markedly higher (p < 0.01) in Meishan and Fengjing boars than in other breeds, and concentrations were nearly 8-fold higher in Meishan than in Duroc boars. Breed differences in serum inhibin were essentially the inverse of those observed for FSH, with Durocs exhibiting the highest inhibin concentrations and Meishans exhibiting the lowest. Testosterone values were not different between breeds. However, testosterone concentrations fluctuated with season, and serum testosterone was highest during the fall of the year in all breeds. These results indicated that some reproductive characteristics differ dramatically between Duroc and Chinese breeds of boars. Breed differences existed in body size, testis size, sperm per ejaculate, ejaculate volume, and serum FSH and inhibin concentrations.(ABSTRACT TRUNCATED AT 250 WORDS)

Seasonal variation in sperm characteristics of boars in southern Uruguay

“…Heterosis may result in an increase in testicular mass, affecting the number of spermatozoa produced (Smital, 2009). However, a negative relationship between testis mass and number of spermatozoa has also been reported (Borg et al, 1993).…”

“…Temperature and photoperiod show the most important effects on pigs (Kozdrowski and Dubiel, 2004;Rivera et al, 2005). It is suggested that photoperiod may play an important role, especially in temperate climates, due to the significant differences in day length over the year (Kunavongkrit et al, 2005 Sperm volume and concentration are lowest in the spring; they gradually increase during the summer, and reach a peak in late autumn (Trudeau and Sanford, 1986;Borg et al, 1993;Kozdrowski and Dubiel, 2004). Changes in the photoperiod cause variations in semen production (Mazzarri et al, 1970) and volume, and spermatozoa abnormalities (Sancho et al, 2004).…”

Age-related Changes of Reproductive Hormones in Young Meishan Boars

“…Meishan sows have also been reported to have higher levels of estradiol-17β, progesterone and inhibin than European sows [5]. However, the plasma concentrations of inhibin in Meishan boars have been shown to be lower than in European breeds [4,12].…”

“…novel because there is currently only data available for adults [4,12]. A negative correlation between inhibin and age has been reported in boys, bulls, and rats [18][19][20].…”

Frequency of Boar Ejaculate Collection and its Influence on Semen Quality, Pregnancy Rate and Litter Size

“…The improvement of quality and economics is limited by the number of insemination doses that can be obtained from one ejaculate and the number of appropriate quality ejaculates that can be obtained from a boar per week. Sperm production and its quality are influenced by many environmental factors such as the season (Love et al 1993;Ciereszko et al 2000;Corcuera et al 2002), breed (Borg et al 1993), age (Swierstra 1973), photoperiod (Sancho et al 2004;Andersson et al 1998), ambient temperature (Corcuera et al 2002), food intake (Kemp et al 1988), breed and testis size (Colenbrander et al 1990;Colenbrander et al 1993). One of the most important factors is the collection frequency, which determines both quantity and quality of sperm and, presumably, the number of spermatozoa in the ejaculate (Swierstra and Dyck 1976).…”