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

Intermittent suckling with or without co-mingling of non-littermate piglets before weaning improves piglet performance in the immediate post-weaning period when compared with conventional weaning

Background: In this experiment, intermittent suckling (IS) with or without the co-mingling (CoM) of piglets was studied as a method to stimulate solid feed intake and reduce post-weaning stress. Methods: Three weaning regimes using 30 multiparous sows were compared: (1) conventional weaning (CW) (n = 10 litters), where piglets had continuous access to the sow until weaning (d 0, farrowing = d −25 relative to weaning); (2) intermittent suckling (IS) (n = 10 litters), where piglets were separated from the sow for 8 h/d starting at d −7 (relative to weaning); and (3) intermittent suckling with co-mingling (ISCo) (n = 10 litters) where IS started at d −7 and two litters were housed together during separation and then returned to their original sow. Ad libitum creep feed was available from d −17. At weaning pigs were housed in pens of 11 pigs, 27 pens in total. The ISCo treatment was divided in half to examine effects of different mixing strategies after weaning. Half of the ISCo litters were kept in familiar groups (ISCoF, familiar, n = 4) and the other half were mixed within treatment resulting in groups of unfamiliar pigs (ISCoNF, not familiar, n = 5), the same as IS (n = 9) and CW (n = 9) treatments. Results: The ISCo piglets ate more creep feed in the week before weaning (P < 0.01), but also showed more aggressive and manipulative behaviour on first day of CoM compared with CW piglets (P < 0.05). IS with or without CoM increased exploratory and play behaviour on the first day of treatment intervention (P < 0.001) and increased sleeping behaviour on the last day of treatment intervention compared with CW (P < 0.001). Mixing strategy at weaning had an effect on performance data with the highest growth and feed intake seen in ISCoF pigs 2 to 8 d after weaning (P <0.001). IS and ISCoNF pigs also grew faster and ate more than CW pigs 2 to 8 d after weaning (P < 0.001). Post-weaning injury scores suggested reduced aggression in ISCo as evidenced by reduced redness (skin irritation) (P < 0.05), and a tendency for ISCo to have less scratches than CW (P < 0.1). The IS pigs slept the most and displayed less manipulative behaviours on the day of weaning and plasma haptoglobin levels remained low in IS pigs after weaning (P ≤ 0.01). Conclusions: Both intermittent suckling techniques improved production indices in the immediate post-weaning period. However, the addition of co-mingling before weaning in combination with grouping familiar pigs together after weaning improved performance in an additive manner

Improving welfare and production in the peri-weaning period: Effects of co-mingling and intermittent suckling on the stress response, performance, behaviour, and gastrointestinal tract carbohydrate absorption in young pigs

We investigated the effect of different pre-weaning interventions on performance, aspects of behaviour, and selected neuroendocrine, inflammatory and immune indices in 593 weanling pigs (59 litters, weaning age 22 ± 1.7). Measurements were taken at various time points two weeks before and after weaning. Sugar absorption tests (20% mannitol and 20% galactose solutions) were used to assess gastrointestinal tract (GIT) absorptive capacity. One week before weaning, litters were either co-mingled (CoM) for 8 h daily with another litter or not co-mingled (NoCoM). Half of the litters were also subjected to intermittent suckling (IS) involving separation from their sow for 8 h daily and the other half remained with their sow (NoIS). Hence, four treatments were produced in a 2×2 factorial design; (1) CoM IS (n = 16 litters), (2) CoM NoIS (n = 14 litters), (3) NoCoM IS (n = 16 litters), (4) NoCoM NoIS (n = 13 litters). Measurements are compared within each of the main effects (CoM or IS) unless otherwise stated. Acute weaning stress was evidenced by increases in cortisol, haptoglobin and N: L ratios when data were combined (P < 0.001). However, there were tendencies (P < 0.1) for lower cortisol in IS pigs and higher N: L ratios in CoM pigs at weaning. While CoM did not affect performance before weaning, growth (P < 0.05), feed intake (P < 0.05) and body weight (P < 0.05) were reduced in CoM pigs 7-14 days after weaning. One week of IS before weaning improved feed intake before weaning (P < 0.01), resulting in better growth (P = 0.01) and a tendency (P < 0.1) for a higher feed intake 2-7 days after weaning. Co-mingled piglets had more scratches 4 days before weaning (P < 0.001), but tended to have fewer scratches 2 days after weaning (P < 0.1). Pigs exposed to either IS or CoM displayed more sleeping behaviour the day after weaning (P < 0.01 and P < 0.001). A higher mannitol absorption was evident in CoM NoIS pigs 3 days after weaning (P < 0.01), and galactose absorption was reduced in IS pigs 3 days before weaning (P < 0.05) and tended to be reduced 3 days after weaning (P < 0.1), likely reflecting a GIT adaptive response. Overall, despite improvements in mannitol absorption and behaviour, there was no beneficial effect of CoM on performance after weaning. Alternatively, IS improved behaviour and performance during the first week after weaning

Intermittent suckling in combination with an older weaning age improves growth, feed intake and aspects of gastrointestinal tract carbohydrate absorption in pigs after weaning

This study tested the hypothesis that intermittent suckling (IS) with or without an older weaning age would improve post-weaning gastrointestinal tract (GIT) carbohydrate absorptive capacity in pigs while reducing post-weaning stress and aspects of the inflammatory response. Three weaning regimes using primiparous sows were compared: (1) conventional weaning (CW28) (n = 22), where piglets were weaned conventionally at day 28; (2) IS28 (n = 21), where IS started at day 21 until weaning at day 28; and (3) IS35 (n = 21), where IS started at day 28 until weaning at day 35. Sugar absorption tests (10% mannitol or 10% galactose) were used to measure GIT absorptive capacity. All measured parameters were compared in relation to weaning across treatments (i.e., different physiological ages were compared). The IS35 pigs grew fastest in the 12 days after weaning (p < 0.01) and had the highest solid feed intake before and after weaning (p < 0.05). Irrespective of treatment, pre-weaning mannitol levels were higher than post-weaning levels (p < 0.01), whereas post-weaning galactose levels were highest in IS35 pigs (p < 0.01). Cytokine data did not show any treatment effects. In conclusion, these data suggest that IS in combination with an older weaning age (day 35) improved post-weaning adaptation as evidenced by improvements in performance measures and galactose absorption. However, IS28 did not improve post-weaning performance

Is there a future for the boar? : the role of boar stimuli in reproductive processes around estrus in the pig

This thesis describes several boar stimuli in their potency to elicit estrous behavior and their potency to affect uterine contractility. With different levels of boar stimuli, onset of estrus can be recorded at different time points relative to ovulation, depending on the change in responsiveness of sows to the stimuli. However, the onset of estrus recorded in such ways, as well as the change in responsiveness recorded by using different stimuli to induce estrous behavior, appeared to be bad predictors for the time of ovulation. Time of ovulation is important for the success of insemination. The use of a back pressure test in the presence of a boar appeared to be most appropriate for detection of estrus, as with lower levels of boar stimuli the chance of not detecting estrus increases, and higher levels of stimuli did not add to the efficiency of estrus detection due to habituation. Uterine contractility is increased during estrus and is important for sperm transport, as suppression of uterine contractility reduces fertilisation rate. Stimulation of uterine contractility to a high degree on the other hand, can obstruct the uptake of the inseminate and increase the reflux of semen. Presence of a boar is more potent than 5-androstenon or tactile stimuli in inducing the release of oxytocin and in stimulating uterine contractility. Moreover, boar presence selectively stimulates uterine contractility only in sows that have a below average uterine contractility, and might therefore be an appropriate way of stimulating uterine contractility during insemination

A new CT-based method to quantify radiation-induced lung damage in patients

SummaryA new method to assess radiation-induced lung toxicity (RILT) using CT-scans was developed. It is more sensitive in detecting damage and corresponds better to physician-rated radiation pneumonitis than routinely-used methods. Use of this method may improve lung toxicity assessment and thereby facilitate development of more accurate predictive models for RILT

Progesterone and Luteinizing hormone secretion patterns in early pregnant gilts

Abstract We studied luteinizing hormone (LH) pulsatility and episodic progesterone release of the corpus luteum (CL) on Day 11 and Day 21 in inseminated gilts and aimed to establish a relationship between these two hormones. Blood was collected at 15-minute intervals for 12 hours on Days 11, 16, and 21 from a vena cava caudalis catheter. At euthanasia eight gilts were pregnant and six gilts were not pregnant. Progesterone parameters (basal, mean, pulse frequency, and pulse amplitude) did not differ between pregnant and non-pregnant gilts on Day 11, LH pulse frequency and amplitude tended to differ (p = 0.07 and p = 0.079). In pregnant gilts basal and mean progesterone, progesterone pulse amplitude and frequency declined significantly from Day 11 to Day 21 (p <0.05). A significant decline was also seen in the LH pulse amplitude from Day 11 to Day 21 (p <0.05). None of the LH pulses was followed by a progesterone pulse within 1 hour on Day 21. On Day 11 and Day 21 appeared a synchronicity in the LH pulse pattern, as there were two or three LH pulses in 12 hours and these LH pulses appeared in the same time window. We conclude that on Day 11 and Day 21 of pregnancy in gilts progesterone pulses do not follow an LH pulse within one hour. Further we demonstrated that the successful or not successful formation of a CL of pregnancy is independent of progesterone release on Day 11 after insemination. We confirmed the decline of progesterone from Day 11 to Day 21 in the vena cava caudalis and could demonstrate that this decline is partly due to lower progesterone pulse amplitude and frequency and that the decline occurs simultaneously with a decline in LH pulse amplitude.Peer reviewe

Breast cancer radiotherapy and the risk of acute coronary events - insights from a process oriented model

BACKGROUND AND PURPOSE: Acute coronary events (ACEs) are considered the most important side effect of radiotherapy (RT) for breast cancer but underlying mechanisms still have to be identified. Process oriented models mathematically describe the development of disease and provide a link between mechanisms and subsequent risk. Here, this link is exploited to learn about the underlying mechanisms from the observed age-time patterns of ACE risk. MATERIALS AND METHODS: A process oriented model of atherosclerosis and subsequent ACEs was applied to a contemporary breast cancer cohort of 810 patients with measurements of coronary artery calcification. Patients with prior ischemic heart disease were excluded. The process oriented model describes disease development as a series of different stages. Different variants of the model were fitted to the data. In each variant, one stage was assumed to be accelerated in relation to mean heart dose. RESULTS: During a mean follow up of 9.1 years, 25 ACEs occurred. The model reproduced the prevalence and associated risk of coronary calcifications. Mean heart dose significantly improved the fit only when implemented as affecting a late stage of atherosclerosis on already existing, complicated lesions (achieving p = 0.007). This can be understood by atherosclerosis being a slowly progressing disease. Therefore, an increase of ACEs few years after RT requires advanced atherosclerosis at the time of RT. CONCLUSION: Risk of ACE increases within few years in patients with advanced atherosclerosis at RT. Therefore, patients should be assessed for cardiovascular risk, and also elderly patients need to be considered for heart sparing techniques

Model-based comparison of organ at risk protection between VMAT and robustly optimised IMPT plans

The comparison between intensity-modulated proton therapy (IMPT) and volume-modulated arc therapy (VMAT) plans, based on models of normal tissue complication probabilities (NTCP), can support the choice of radiation modality. IMPT irradiation plans for 50 patients with head and neck tumours originally treated with photon therapy have been robustly optimised against density and setup uncertainties. The dose distribution has been calculated with a Monte Carlo (MC) algorithm. The comparison of the plans was based on dose-volume parameters in organs at risk (OARs) and NTCP-calculations for xerostomia, sticky saliva, dysphagia and tube feeding using Langendijk's model-based approach. While the dose distribution in the target volumes is similar, the IMPT plans show better protection of OARs. Therefore, it is not the high dose confirmation that constitutes the advantage of protons, but it is the reduction of the mid-to-low dose levels compared to photons. This work investigates to what extent the advantages of proton radiation are beneficial for the patient's post-therapeutic quality of life (QoL). As a result, approximately one third of the patients examined benefit significantly from proton therapy with regard to possible late side effects. Clinical data is needed to confirm the model-based calculations