Breeding and genetics Nutrition Aquaculture and Fisheries Adaptation Physiology Cell Biology and Immunology Experimental Zoology Department of Animal Science Wageningen University

Intermittent suckling: possibilities to establish pregnancy during lactation & benefits to piglets Marieke Berkeveld Rosemarijn Gerritsen Pieter Langendijk In cooperation with Veterinary Faculty in Utrecht

Weaning-induced growth check after Weary et al., 2002 weaning

Bruininx et al., 2002 Feed intake shortly after weaning Many piglets hardly eat after weaning

Weaning related problems, due to age at weaning not familiar with dry feed … Possible solution: Make pigs familiar with dry feed before weaning

Intermittent suckling: Suckling inhibited for 12 h per day from D14 of lactation

Feed intake before and after weaning Eat before weaning = eat after weaning Kuller et al., 2000

Feed intake before and after weaning Kuller et al., 2000

Distribution of feed intake during lactation Kuller et al., 2000 Intermittent suckling increases feed intake during lactation

Intermittent suckling increases feed intake during lactation, But weaning at conventional age still induces a growth check Possible solution: Also extend lactation without postponing next pregnancy

Growth in the IS model

Feed intake in the IS model

Relative growth from milk and dry feed

Conclusions Intermittent suckling results in better adaptation to weaning: Feed intake at weaning is considerably higher than normally There is hardly any growth check at weaning If sow is mated, lactation can be extended Consequences for reproduction ?

SourceStage of lactation h IS/day Boar contact? Sows in estrus Crighton, 1970D21-D3112yes1/5 Stevenson and Davis, 1984D14-D no 13/20 5/10 Grinwich and McKay, 1985D21-D yes <10% ±80% Newton et al., 1987aD13-D yes no 13/30 15/19 5/28 4/28 Newton et al., 1987bD20-D286yes10/10 Kuller et al., 2004D16-D2712no11/49 Past experience with IS

Litter separation –Number of sows with estrus: VARIABLE –Occurrence of estrus: ASYNCHRONISED Important factors –Stage of lactation –Duration of separation –Boar contact –Parity –Breed –… Past experience with IS

Intermittent suckling model Intermittent suckling from D14 (or later) of lactation: Suckling inhibited for 12 h: IS12: IS6: and Weaning at 6 w of lactation Reference: continuous lactation and weaning at 21 d Dalland sows

614 B LO D6.5 20:00 8:00 20:004:00 START IS period of suckling LH (ng/ml) Day 1 LH secretion during IS regime

N=6 N=5 * * * * Cortisol secretion during IS regime TOTSEP: sows taken away from farrowing unit PHYSEP: sows only separated physically from piglets *treatment effect Total separation more effective in triggering LH release and increased chance of estrus

CIS12IS6 # sows in exp start IS/weaning lactational oestrus (%) 26%100%92% oestrus after weaning (%) 74%-- ovulation (%)100%93%83% cystic follicles014* *2 of 4 sows ovulated and developed cystic follicles Estrus and ovulation

Follicle development during IS regime

Peri-ovulatory endocrine changes

Estradiol

Pre-ovulatory LH surge *

Post-ovulatory progesterone rise * * * * *

Cystic sows

LH surge and progesterone after ovulation are lower in the IS regime This does not seem to influence the number of sows ovulating and showing estrus Although IS6 sows seem to run a higher risk of developing cysts, and have delayed LH surge, estrus, and ovulation What about pregnancy?

C (n=16)IS12 (n=9)IS6 (n=7) Pregnant D23 (%) 94%77%78% Ovulation rate 25± ± ±2.6 Embryonic survival (%) 62±658±657±7 a,b different superscripts in one row P<0.05 Conception

a,b different superscripts in one row P<0.05, c,d different superscripts in one row P<0.10 Treatment C (n=16)IS12 (n=9)IS6 (n=7) Embryo weight (g)0.20 ± 0.01 a 0.18 ± 0.02 a,b 0.14 ± 0.01 b Rump length (mm)19.5 ± ± ± 0.5 Placental length (cm) 20.4 ± 0.9 a,cd 19.7 ± 1.1 ab,c 15.9 ± 1.1 b,d Implantation area (cm 2 ) ± 6.5 a ± 8.0 a,b 92.1 ± 8.5 b Embryo development

Lactational estrus/ovulation easily induced in IS12 model Ovulation IS6 sows seems affected Pregnancy rate (?) and early embryonic survival not affected in IS12 Placental characteristics, embryonic development seems affected by IS6 But: LH surge? – stage of lactation Progesterone output? – LH surge, feed intake, growth factors All breeds? Conceptus development during later stages of gestation? Preliminary conclusions

Feed intake afer ovulation and progesterone High/low feed intake from O to 6d after ovulation, subsequently weaning High: fed to requirementsLow: High – 2.5 kg

Restoration of preovulatory LH centre in Hypothalamus. Bevers et al. 1981

LH surge and luteal function

Stage of lactation influences LH surge and luteinisation? 3 treatments: 1. IS starts at D14 2. IS starts at D21 3. Control weaned at D21 New experiment

IGF around weaning weaning

IGF and luteal function 2004: IS model 2005: IS model 1997: weaned, primiparous sows

Stage of lactation influences LH surge and luteinisation? 3 treatments: 1. IS starts at D14 2. IS starts at D21 3. Control weaned at D21 New experiment Wean at ovulation or 30d after

BOARNO BOAR N=16 Spontaneous ovulation54 Cystic11 Anovulatory1011 Treated with PG600*99 *Of the 21 anovulatory sows, 3 sows were removed from the experiment before treatment with PG600 Sows with ovulation showed estrus, whereas anovulatory sows did not IS in a different breed IS12 model, using Dutch Landrace x Yorkshire Boar contact 3x/d, from start of IS (D14)

ovulation no ovulation cystic Estradiol

min max Follicle development

Estradiol in relation to follicle growth

IS model is promising, but room for improvement Timing of start of IS – luteinisation Timing of weaning – developing conceptus Breed differences Conclusion

Thank you !

Nutrients and villous atrophy The drop in nutrient supply is a major cause of intestinal atrophy Van Beers-Schreurs, 1998 Day 4 ME intake kJ/BW 0.75 UW unweaned SMH sow milk high WD weaned on dry feed SML sow milk low

SISP – small intestine segment perfusion test Kuller et al., 2002

Feed intake and absorptive function Kuller et al., 2002 Piglets that eat already during lactation have better intestinal absorptive function post weaning

Intermittent suckling From 2 weeks of lactation, sows and piglets are separated for 12 h per day