Reproductive management in pigs: emphasis on the different roles of the boar and on optimal insemination management

Boars have different roles in the reproductive management in pigs. Boar contact can stimulate follicle development and thereby induce oestrus, both in gilts and sows. Boar contact during oestrus is essential for good oestrus expression, which is essential for the correct timing of insemination and the proper use of boar contact during insemination can stimulate sperm transport and thereby fertilisation. Stimulation by boars clearly has an olfactory component (the boar smell), but can also have an auditory, visual and evn tactile component. The background of the different roles and some of these different components of the boar are discussed. To enable a good farrowing rate and litter size, sows should be inseminated between 0 and 24h before ovulation. However, it is not possible to accurately predict the time of ovulation in sows. Although ovulation takes place at a relatively fixed 60-75% of the duration of oestrus, the duration of oestrus varies considerably between sows and between farms, resulting in a variable ovulation time from onset of oestrus. Therefore, most farmers inseminate their sows every day of oestrus to ensure insemination within the optimal period. Since post-ovulation inseminations should be avoided, it is adviced to only inseminate sows while they still show an optimal standing respons

Effecten van eenvoudige koolhydraten en fermenteerbare koolhydraten op de binnentoom variatie bij varkens

2 proeven werden uitgevoerd. Het doel van de 1e was nader inzicht te krijgen in het mechanisme dat ten grondslag ligt aan de relatie tussen insuline-stimulerend voer (dextrose+lactose) tijdens het interval spenenovulatie, follikelontwikkeling in de laatste dagen voor inseminatie en (variatie in) ontwikkeling van embryo's tijdens de vroege dracht. Het doel van de 2e proef was om nader inzicht te krijgen in de directe effecten van de specifieke voercomponenten dextrose, lactose, sucrose en suikerbietenpulp (zowel apart als gecombineerd) op glucose, insuline en IGF-1 profielen in zeugen om zo diëten te vinden met de hoogste potentie om insuline en IGF-1 afgifte te stimuleren

The second litter syndrome in sows; causes, consequences and possibilities of prevention

Second parity sows may have suboptimal farrowing rate and litter size, resulting from relatively high weight losses during first lactation. Sows with low performance in second parity on average also have a lower performance in later parities and increased chances of early culling. To overcome this reduced second parity reproductive performance, feed intake during first lactation needs to be improved. To realise this, both pre-farrowing and lactational –nutritional- management needs to be optimised. On the other hand, also post-weaning management strategies can influence second parity performance. Improved follicle recovery prior to insemination can be achieved by applying either skip-a-heat, or daily altrenogest treatments. These both postpone insemination time after oestrus, resulting in improved performance

Follicular development of sows at weaning in relation to estimated breeding value for within-litter variation in piglet birth weight

In this study we aimed to identify possible causes of within-litter variation in piglet birth weight (birth weight variation) by studying follicular development of sows at weaning in relation to their estimated breeding value (EBV) for birth weight variation. In total, 29 multiparous sows (parity 3 to 5) were selected on their EBV for birth weight variation (SD in grams; High-EBV: 15.8±1.6, N=14 and Low-EBV: −24.7±1.5, N=15). The two groups of sows had similar litter sizes (15.7 v. 16.9). Within 24 h after parturition, piglets were cross-fostered to ensure 13 suckling piglets per sow. Sows weaned 12.8±1.0 and 12.7±1.0 piglets, respectively, at days 26.1±0.2 of lactation. Blood and ovaries were collected within 2 h after weaning. The right ovary was immediately frozen to assess average follicle size and percentage healthy follicles of the 15 largest follicles. The left ovary was used to assess the percentage morphologically healthy cumulus-oocyte complexes (COCs) of the 15 largest follicles. To assess the metabolic state of the sows, body condition and the circulating metabolic markers insulin, IGF1, non-esterified fatty acid, creatinine, leptin, urea and fibroblast growth factor 21 were analysed at weaning. No significant differences were found in any of the measured follicular or metabolic parameters between High-EBV and Low-EBV. A higher weight loss during lactation was related to a lower percentage healthy COCs (β= −0.65, P=0.02). Serum creatinine, a marker for protein breakdown, was negatively related to average follicle size (β= −0.60, P=0.05). Backfat loss during lactation was related to a higher backfat thickness at parturition and to a higher average follicle size (β=0.36, P<0.001) at weaning. In conclusion, we hypothesise that modern hybrid sows with more backfat at the start of lactation are able to mobilise more energy from backfat during lactation and could thereby spare protein reserves to support follicular development.</p