A genome-wide linkage analysis for reproductive traits in F2 Large White × Meishan cross gilts

Female reproductive performance traits in pigs have low heritabilities thus limiting improvement through traditional selective breeding programmes. However, there is substantial genetic variation found between pig breeds with the Chinese Meishan being one of the most prolific pig breeds known. In this study, three cohorts of Large White × Meishan F(2) cross-bred pigs were analysed to identify quantitative trait loci (QTL) with effects on reproductive traits, including ovulation rate, teat number, litter size, total born alive and prenatal survival. A total of 307 individuals were genotyped for 174 genetic markers across the genome. The genome-wide analysis of the trait-recorded F(2) gilts in their first parity/litter revealed one QTL for teat number significant at the genome level and a total of 12 QTL, which are significant at the chromosome-wide level, for: litter size (three QTL), total born alive (two QTL), ovulation rate (four QTL), prenatal survival (one QTL) and teat number (two QTL). Further support for eight of these QTL is provided by results from other studies. Four of these 12 QTL were mapped for the first time in this study: on SSC15 for ovulation rate and on SSC18 for teat number, ovulation rate and litter size

A revised list of alien plants for the Kruger National Park

Alien plants recorded in the Kruger National Park are listed, providing an update of species that have been recorded since the last published list in 1988. The serious consequences that invasive alien plants pose are widely recognised internationally and are regarded as the greatest threat to the Kruger National Park. It is extremely important to maintain an updated list of species to use as a reference and from which to monitor changes in the influx of invasive species. The list contains the invasive status of the plants, current impact, habitat types, biological control status and status according to the Conservation of Agricultural Resources Act (CARA), Act 43 of 1983, as amended in March 2001. The list comprises 370 species, of which 121 are invaders and two are transformer weeds, which may cause considerable damage and alterations to the indigenous biodiversity. A total of 91 species listed herein are also listed in the CARA regulations or are proposed additions to the CARA regulations

Feeding lactating primiparous sows to establish three divergent metabolic states: I. Associated endocrine changes and postweaning reproductive performance

We investigated effects of different metabolic states on reproductive performance in lactating, primiparous sows. Sows were fed ad libitum (AL; n = 12), alimentated via a gastric cannula to 125% of AL feed intake (SA; n = 8), or restricted (R; n = 9) to 50% of AL from d 1 to 28 of lactation. At weaning, all sows were fed 2.5x maintenance energy requirements until standing heat and then fed twice maintenance energy requirement until slaughter. Sow weight, backfat, and litter weights were recorded weekly. After weaning, sows were tested twice daily for the onset of estrus and inseminated twice using pooled semen. At d 28 of gestation, sows were slaughtered, and the reproductive tracts were recovered to determine ovulation rate and embryo survival. Intensive blood sampling was performed before and after weaning for 12-h periods to characterize changes in plasma LH, insulin, and IGF-I. After weaning, additional samples were taken to monitor changes in LH and progesterone. Insulin and IGF-I were determined at standing heat. During lactation, AL and R sows lost, whereas SA sows gained, body weight and backfat (P < .001). Litter growth rates did not differ among treatments. Although plasma insulin was not different among treatments, plasma IGF-I concentration was lower (P < .001) in R sows. Mean LH and pulse frequency before (P < .03 and P < .06, respectively) and after (P < .001; for both) weaning were lower in R than in AL or SA sows. After weaning, SA sows lost more weight (P < .01) and backfat (P < .01) and ate less feed (P < .001) than AL or R sows. At standing heat, no differences in plasma IGF-I or insulin were observed, although energy balance for SA sows was lower (P < .01) than for AL or R sows. Weaning-to-estrus interval was extended (P < .02) in R sows. We observed no treatment difference in ovulation rate or embryo survival. Our results demonstrate that making sows anabolic during lactation did not ameliorate the negative impact of the suckling stimulus or improve fertility after weaning

LH and FSH secretion, follicle development and oestradiol in sows ovulating or failing to ovulate in an intermittent suckling regimen

The present paper describes LH and FSH secretion, follicle development and ovulation in sows that were subjected to a limited nursing regimen. From Day 14 of lactation, 32 sows were separated from their piglets for 12 h every day (intermittent suckling; IS). Half the sows had boar contact during separation. Nine of 32 sows ovulated spontaneously within 14 days from initiation of IS. The frequency of LH pulses on the first day of IS tended to be higher in anovulatory sows (6.3 v. 4.2 pulses per 12 h; P <0.10); other characteristics of LH secretion were similar to sows that ovulated. The characteristics of FSH secretion did not differ over the 8-h sampling period. Boar contact did not influence either LH and FSH secretion or the number of sows that ovulated. Up to 58% of anovulatory sows showed an increase in follicle size after initiation of IS and, 4 days after the initiation of IS, one-third still had follicles similar in size to those in ovulatory sows. However, the oestradiol concentration in anovulatory sows did not increase. We conclude that FSH and LH stimulation in anovulatory sows is not limiting for normal follicle development, but that ovarian follicles are not responsive to increased LH secretio