Reproduction performances and conditions of group-housed non ...

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- Paper I - gonadotrophins (LH, FSH) (Hughes & Pearce, 1989). Both LH and FSH act on the ovaries to stimulate the development of the pre-ovulatory follicle (Foxcroft & Hunter, 1985). LH is furthermore essential for the maintenance of early pregnancy in the pig (Peltoniemi et al., 1995) why lower pregnancy rate as a consequence of restricted feed intake may be due to a reduction in LH pulse frequency (Peltoniemi et al., 2000). The negative effect of high feed intake the first three days in pregnancy on embryo survival is believed to be caused by an increase in hepatic blood flow and metabolic clearance rate of progesterone, as a consequence of rapid weight gain, followed by a decrease in plasma level of progesterone (Hughes & Pearce, 1989; Foxcroft, 1997). Progesterone is the primary director of uterine development and secretion (Geisert & Yelich, 1997) and therefore a change in plasma level of progesterone could imply detrimental consequences for embryo survival as indicated in a study by Pharazyn et al. (1991). Progesterone is secreted from Corpus Luteum and because the pig is polyovulatory, it is suggested that it is unlikely that the plasma progesterone concentration may get below some essential threshold after the first three to four days of pregnancy (Foxcroft, 1997). The statement, that reproduction may be influenced by nutrition is further supported by observations of wild sows. Matschke (1964 q.f. Graves, 1984) reported that European wild sows were anoestrous during years of small quantity of mast and similar did Mauget (1981) report that the timing of breeding season was influenced by the amount of mast available. When looking upon the results from the studies reviewed, although it does not provide a clear picture, it seems that pregnancy rate and litter size can be influenced by energy intake in the non-lactative period. However, the question, which remains to be answered, is whether variation in energy intake between female pigs in commercial group-housed systems reaches magnitudes large enough to impair the litter size and pregnancy rate? Andersen et al. (1999) observed that low ranking sows only spent about half as much time at the trough at feeding compared to high ranking sows (40 vs. 90 % of observations) in a group of pregnant sows. Although low ranking sows may be able to increase their eating rate when competition for feed is high, as suggested by Brouns & Edwards (1994), it is likely that the energy intake of the low ranking sows has been considerably lower than the energy intake of the high ranking sows. Mendl et al. (1992) observed that low and none success primaparous sows (the sows were divided into three groups according to their ability to displace other sows in agonistic interactions) had significant lower weight gain than high success primaparous sows (approximately 7, 9 and 19 kg, respectively in one month) in their 7 th week of pregnancy. As Mendl et al. (1992) point out, the lower weight gain in the low ranking sows is not necessarily a result of lower feed intake only but perhaps a combination of lower feed intake and an elevated expenditure of energy for maintenance as 39
- Paper I - a consequence of stress. However, no matter what may have caused the lower weight gain, the result would be less energy substrates available for the physiological processes related to reproduction. In the study by Brouns & Edwards (1994), the weight gain throughout gestation in the low ranking sows was only 60% (28.3 vs. 46.6 kg) and 50% (22.4 vs. 44.9 kg) of the weight gain of the high ranking sows, respectively in two different experimental pens. The total gain of 44.9 kg and 22.4 kg during an entire gestation corresponds with approximately 0.390 kg and 0.195 kg daily gain, respectively. The groups consisted of multiparaous sows and the ranking order was significantly correlated with initial live weight of the sows (Brouns & Edwards, 1994). According to Danielsen (personal communication, 2003), one kg of gain in gestation requires 14 MJ ME, for which reason 0.390 and 0.195 kg of gain would require 6 and 3 MJ ME, respectively. Assuming that high ranking sows weighted about 260 kg and low ranking sows 200 kg, the daily energy requirement for maintenance for high and low ranking sows would be approximately 27 MJ ME and 23 MJ ME, respectively (Just et al., 1983; Theil et al., 2002; Danielsen, personal communication 2003). Estimated energy intake for low ranking sows would therefore be approximately 80 % of the energy intake of the high ranking sows (26 and 33 MJ ME, respectively). In commercial practice, the difference between high and low ranking sows’ feed intake during pregnancy may, under some circumstances, be higher than indicated in the studies by Andersen et al. (1999) and Brouns & Edwards (1994). In these studies, the group size was six and 12 sows, respectively, whereas in commercial sow herds, floor feeding is also practiced in larger groups. If the feed is provided on a small area, it is likely that the more sows in the group, the higher the risk that the low ranked sows are kept away from the feeding place. Experiences from practical husbandry indicate that a huge variation in weight between sows causes more aggressions and displacements at feeding compared to more uniform groups (Olsson & Svendsen, 1997). Therefore, the magnitude of the variation in energy intake between group housed sows will probably not only depend upon feeding procedure but also on group size and group composition and then vary considerably between herds but also within herds between farrowing batches. It is generally recommended to feed pregnant sows in the range of 25-35 MJ ME day -1 (NRC, 1998; The National Committee for Pig Production, 2003b). If sows for instance are provided with 30 MJ ME day -1 , and assuming that the low ranking sows only eat approximately 50-80% of the portion that high ranking sows as indicated in the studies by Andersen et al. (1999) and Brouns & Edwards (1994), this means that high ranking sows would consume 33-40 MJ ME day -1 and low ranking sows 20-26 MJ ME day -1 in average. In gilts, an energy intake of 33-40 MJ ME day -1 could have a negative influence on litter size if it occurs the first three days after mating. An energy intake of 20-26 MJ ME day -1 40
Page 1 and 2: Reproduction performances and condi
Page 4: Contents Summary………………
Page 7 and 8: Paper II - Summary - A review of 15
Page 10 and 11: - Sammendrag - SAMMENDRAG Antallet
Page 12: - Sammendrag - søgt. Positive korr
Page 15 and 16: - Background and aim - systems and
Page 18: - Outline of this thesis - OUTLINE
Page 21 and 22: - How does group housing vary in pr
Page 23 and 24: - How does group housing vary in pr
Page 26 and 27: - Paper I - Effect of energy intake
Page 28 and 29: - Paper I - 1. Introduction The num
Page 30 and 31: - Paper I - Therefore, the aim of t
Page 32 and 33: Refer ence Table 1. Effect of energ
Page 34 and 35: - Paper I - Therefore, low energy s
Page 36 and 37: Table 2. Effect of energy intake in
Page 38 and 39: - Paper I - However, this does not
Page 40 and 41: Table 3. Effect of energy intake in
Page 42 and 43: - Paper I - Feeding sows 16, 27 or
Page 46 and 47: - Paper I - the first four weeks af
Page 48 and 49: - Paper I - Cosgrove, J.R., Foxcrof
Page 50 and 51: - Paper I - Matschke, G.H., 1964. T
Page 52: - Paper I - Tribble, L.F., Orr, D.E
Page 55 and 56: - Paper III - Indicators of feed in
Page 57 and 58: - Paper III - 1. Introduction The n
Page 59 and 60: Table 1. Applied feeding and housin
Page 61 and 62: - Paper III - performed. The sow ha
Page 63 and 64: - Paper III - proximately three wee
Page 65 and 66: - Paper III - Table 3. Overall mean
Page 67 and 68: Table 5. Correlations between all c
Page 69 and 70: Back fat W, mm Back fat gain, AM-F,
Page 71 and 72: - Paper III - from three weeks afte
Page 73 and 74: - Paper III - Number of skin lesion
Page 75 and 76: - Paper III - In herds practising g
Page 77 and 78: - Paper III - Previous work have fo
Page 79 and 80: References - Paper III - Andersen,
Page 81 and 82: - Paper III - Kongsted, A.G. 2004a.
Page 83 and 84: - Paper IV - Relation between repro
Page 85 and 86: - Paper IV - 1. Introduction Group
Page 87 and 88: - Paper IV - ing compared to number
Page 89 and 90: - Paper IV - mixed model using the
Page 91 and 92: Table 2. Estimates and standard err
Page 93 and 94: - Paper IV - cial effect on high ra
Page 95 and 96:
References - Paper IV - Aherne, F.X
Page 97 and 98:
- Paper IV - Olsson, A.-C., Svendse
Page 99 and 100:
- General discussion - GENERAL DISC
Page 101 and 102:
- General discussion - However, an
Page 103 and 104:
References - General discussion - A
Page 105 and 106:
- Conclusions - 6. CONCLUSIONS Two
Page 107 and 108:
- Appendix 1 - APPENDIX 1 LITTER SI
Page 109 and 110:
- Appendix 1 - they are mature i.e.
Page 111 and 112:
- Appendix 1 - Soon after ovulation
Page 113 and 114:
- Appendix 1 - Crombie, P.L., 1970.
Page 115:
- Appendix 1 - Scott, M.A., 2000. A
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