Nutrition of gilts in early pregnancy and reproductive performance Pieter Langendijk Rebecca Athorn Tai-Yuan Chen Emmy Bouwman

~300g /d ~500g /d This graph is by no means a recommended feeding strategy !

Current recommendation says: “feed gilts at a low feed level during early gestation” Feed intake early gestation Targets of gestation feed regime: Balanced achievement of pre-farrowing BW Sufficient body reserves Good birth weight Are there risks associated with high/low feed level?

Jindal et al., 1996 Feed level and embryo mortality

Progesterone from the ovaries is broken down in the systemic circulation by the liver Systemic progesterone, ng/ml Systemic progesterone and feed levels

Studies on feeding level 1. Dyck and Strain (1983) 2. Toplis et al. (1983) 3. Pharazyn et al. (1991) 4. Jindal et al. (1996) 5,6. Jindal et al. (1997) 7. Ashworth et al. (1999) 8. Virolainen et al. (2004) 9. Virolainen et al. (2005b) 10. Quesnel et al. (2010) 11,12,13,14. Athorn et al (2011, 2012) pregnancy rate embryo survival First 3 d!

Progesterone in the systemic circulation is broken down by the liver Systemic and local progesterone

Progesterone in the systemic circulation is broken down by the liver Direct transfer of progesterone from the ovaries to the uterus Systemic and local progesterone

Local and peripheral progesterone 5.0 embryos 6.1 embryos

Cannulation of the vena cava 6 h period A high feed level seems to increase progesterone secretion by the ovaries Progesterone in systemic circulation

Luteal mass and progesterone It pays to have more luteal tissue

Effects of feed level on progesterone secretion: Direct increased LH increased luteotrophic factors factors e.g. IGF-1 Indirect Increased luteal tissue mass

R.Z. Athorn, P. Stott, E.G. Bouwman, R. Ashman, S. O’Leary, M. Nottle and P. Langendijk. Direct ovarian-uterine transfer of progesterone increases embryo survival in gilts. Reprod Fertil Dev. 2011, 23, 921–928. Athorn, R.Z., Stott, P., Bouwman, E.G., Chen, T.Y., Kennaway, D.J. and Langendijk, P. (2012) Effect of feeding level on luteal function and progesterone concentration in the vena cava during early pregnancy in gilts. Reproduction, Fertility and Development R.Z. Athorn, P. Stott, E.G. Bouwman, and P. Langendijk. (2012) Effects of energy level and energy source on luteal function and embryo survival in gilts. Submitted to Anim Prod Sci. In Press R.Z. Athorn, P. Stott, RS Smits, and P. Langendijk. Athorn et al Effect of feed level and energy source on pregnancy rate and embryo survival in gilts. In preparation. R.Z. Athorn, P. Stott, RS Smits, and P. Langendijk. Athorn et al Effect of feed level and energy source on pregnancy rate and embryo survival in first litter sows. In preparation.

High (~2.8 kg) Low (~1.4 kg) Exp 1 (Athorn et al, 2011) n15 Total embryo survival (d0-35), % (range) 73 (45-100) 65 (35-93) after implantation (d15-35), % (range) 95 a (80-100) 85 b (50-100) Exp 2 (Athorn et al., 2012) n109 Embryo survival at d , %92 a 77 b a,b Different superscripts within row indicate significant difference (P < 0.05) Feed level and embryo survival

Diet LOW Starch ~1.4 kg HIGH Starch ~2.8 kg HIGH Fat ~2.6 kg HIGH Fibre** ~3.0 kg N Weight gain, g/d320 ± 35 a 1000 ± 55 b 919 ± 53 b 1055 ± 55 b Ovulation Rate15.3 ± ± ± ± 0.4 Total luteal weight, g* 6.7 ± 0.2 x 7.2 ± 0.2 y 7.1 ± 0.2 y 6.8 ± 0.2 x,y Pregnancy rate94% (31/33)91% (21/23)96% (23/24) Total embryos*12.2 ± ± ± ± 0.7 Embryo survival*80 ± 3%77 ± 4%76 ± 4% Feed level/energy source early pregnancy *corrected for ovulation rate, **7.2% fibre, millmix and oat hulls Athorn et al., 2012

N* BW Gain (g/d) Pregnancy rate d28 (%) TBBA Low (21 MJ DE/d) ± 41 a 83 (50/60)12.5 ± ± 0.4 Medium (31 MJ DE/d) ± 45 a 81 (44/54)12.2 ± ± 0.4 High (41 MJ DE/d) ± 40 b 91 (53/58)11.8 ± ± 0.4 Fibre diet (31 MJ DE/d) ± 34 a 82 (50/61)12.3 ± ± 0.4 Feed level/energy source early pregnancy Rivalea, 2010

Pregnancy rate(%) Growth rate to d25 of gestation(%) Growth rate and pregnancy rate P = 0.09

Treatment Control 2.5 kg High 3.25 kg Control 2.5 kg High 3.25 kg Litters at termPregnancy at d35 n BW gain, kg 16 ± ± ± ± 1.1 Back fat gain, mm 1 ± ± ± ± 0.4 FR/PR, % 89 %75 %87 %95 % LS/embryos 13.2 ± 1.2 a 15.2 ± 0.5 b 15.9 ± ± 0.7 Hoving et al., 2011 Extra feed during early pregnancy (d3-25) in first litter sows

New aspect: group housing Thesis by A.G. Kongsted (2005)

“Sows eating less than 20 % of all observations at feeding had significant higher risk of returning to oestrus…” “Positive relationship between back fat gain from weaning to three weeks after mating with chance of pregnancy (P<0.05) and litter size (P=0.08).” (Kongsted, 2005) New aspect: group housing Preganancy chance, % Back fat gain, mm/wk

TreatmentBASBTotal Born Control (n=11) 10.6 ± 0.5 a 0.3 ± ± 0.5 a Fasted (n=11) 8.1 ± 0.8 b 0.7 ± ± 0.8 b Effects of feed incidents

1.High feed levels do not result in higher embryo mortality 2.It is better to recommend moderate to high feed levels: kg per day, rather than low 3.Limit feed intake in late gestation to kg ( MJ DE) 4.There may be a risk associated with low feed (incidents) levels especially in group housing Implications