ABSTRACT De lactatie en de periode vlak na spenen zijn belangrijke fases in het leven van zeugen ... more ABSTRACT De lactatie en de periode vlak na spenen zijn belangrijke fases in het leven van zeugen en biggen. Recent onderzoek aan ondermeer Wageningen UR geeft aanknopingspunten om deze periodes soepeler te laten verlopen voor de zeug en haar biggen
The aim of the study was to measure the effect of creep feeding during lactation on net absorptio... more The aim of the study was to measure the effect of creep feeding during lactation on net absorption in the small intestine at 4 days after weaning. Intermittent suckling was used to increase creep feed intake during lactation. Creep feed containing chromic oxide was provided. Based on the colour of the faeces, piglets were classified as 'eaters' or 'non-eaters', respectively. At day 4 after weaning, an in vivo small intestine segment perfusion test was performed at 5 sites along the small intestine in 24 piglets (12 eaters and 12 non-eaters). At both sides of each intestinal segment a tube was fitted to perfuse and drain fluid in order to assess net absorption. Net absorption was higher in eaters than in non-eaters (P b 0.001). Net absorption varied greatly between and within piglets and was highest in the caudal segments of the small intestine (P b 0.001). These data suggest that creep feeding could be a useful tool in the prevention of post-weaning diarrhoea.
Selection for litter size may result in an increase in uterine crowding due to a faster increase ... more Selection for litter size may result in an increase in uterine crowding due to a faster increase in ovulation rate than in litter size. Increased ovulation rate does not result in a proportionally increased number of piglets born alive. In this study, the effect of ovulation rate on vitality characteristics of fetal-placental units at d 40 of pregnancy was investigated. For this, 43 Large White gilts were treated with hormones to induce superovulation. Average ovulation rate was 45.16 ± 13.22; average number of vital fetuses at d 40 of pregnancy was 17.09 ± 3.61 that weighed 11.26 ± 1.99 g; their placenta weighed 31.88 ± 14.79 g; and they occupied 11.69 ± 4.90 cm of the uterus. Loss in oocytes (i.e., that did not result in a vital fetus at d 40) increased with increasing ovulation rate and occurred before (early mortality; P = 0.0003) and after implantation (late mortality, i.e., traces visible at d 40; P < 0.0001). With respect to the vital fetuses, increased ovulation rate resulted in decreased fetal (P = 0.0008) and placental weight (P = 0.0008) and decreased length of the area in the uterus that was occupied by the placenta (P = 0.0011). Strong correlations existed between placental and fetal weight [0.68; 95% confidence interval (CI) = 0.64 to 0.72], and placental weight and length (0.78; 95% CI = 0.74 to 0.82). Fetal-placental characteristics were weakly correlated to distance to the implantation sites of neighboring fetuses, a measure of crowdedness [−0.002 (95% CI = −0.042 to 0.038) with fetal weight to 0.16 (95% CI = 0.12 to 0.20) with placental length]. Increased ovulation rates, but more specifically increased late mortality rates, have negative effects on the remaining vital fetuses with respect to the fetal (P = 0.0085) and placental weight (P < 0.0001) and length of the implantation site (P = 0.0016). The most extreme effect was on placental weight, in which a uterus with <10 cases of late mortality was on average 25% greater than placental weight in a uterus with >18 cases of late mortality (P < 0.0001). Furthermore, increased ovulation rates resulted in decreased within litter variation for fetal (P = 0.0018) and placental weight (P = 0.0084). At increased ovulation rates, the number of live fetuses remained similar, but placental development is impaired and the growth of the fetus is retarded compared with reduced ovulation rate, with effects likely lasting into adult life.
Piglet birth weight and litter uniformity were studied in sows of different parities and crossbre... more Piglet birth weight and litter uniformity were studied in sows of different parities and crossbred lines in relation to: 1) weaning-to-pregnancy interval (WPI) and 2) sow body condition changes (in BW and backfat thickness) during lactation and gestation in sows with a short WPI (≤7d). At the Institute for Pig Genetics (IPG) research farm, individual piglet birth weights and sow body condition (BW and backfat thickness at farrowing and weaning) were measured for 949 TOPIGS20 and 889 TOPIGS40 sows with &amp;amp;gt;4 total born piglets, inseminated between 2003 and 2011. In all analyses, mean piglet birth weight and birth weight SD and CV were corrected for total number born. Total number born was greater in sows with a WPI of 8 to 21 d (+1.2 piglets; n = 72) and &amp;amp;gt;21 d (+0.7 piglets; n = 182), compared with sows with a WPI ≤7 d (P &amp;amp;lt; 0.01; n = 1,584). Mean piglet birth weight was not affected by WPI. Birth weight SD (-23 g) and CV (-1.7%) were lower in sows with a WPI &amp;amp;gt;21 d, compared with sows with a WPI ≤7 d (P &amp;amp;lt; 0.01). Effects of WPI were independent of sow parity. Effects of body condition changes in sows with a WPI ≤7 d were studied separately in TOPIGS20 sows inseminated between 2006 and 2011 (n = 808), and in TOPIGS40 sows inseminated between 2003 and 2008 (n = 747). Sow body condition loss during lactation was not related with subsequent total number born or mean piglet birth weight. Only in TOPIGS20 sows, more BW loss during lactation was related with greater subsequent birth weight SD (β = 0.83 g/kg, P &amp;amp;lt; 0.01; β = 1.62 g/%, P &amp;amp;lt; 0.01). Additionally, more backfat loss during lactation was related with greater subsequent birth weight SD (β = 5.11 g/mm, P &amp;amp;lt; 0.01) and CV (β = 0.36%/mm, P &amp;amp;lt; 0.01), independent of sow parity. Sow BW increase during gestation was negatively related with total number born [TOPIGS20: β = -0.06 and -0.05 piglet/kg BW increase for parity 2 (P &amp;amp;lt; 0.01), and 3 and 4 (P &amp;amp;lt; 0.01), respectively; TOPIGS40: β = -0.04 piglet/kg BW increase (P &amp;amp;lt; 0.01), independent of sow parity]. Sow BW increase during gestation was positively related with birth weight SD [TOPIGS20: β = 0.63 g/kg BW increase (P = 0.01), independent of sow parity]. Sow body condition increase during gestation was not related with mean piglet birth weight. To conclude, this study shows that litter uniformity is compromised by severe sow body condition loss during lactation and improved in sows with a prolonged WPI. These effects are likely related with (insufficient) restoration of follicle development.
Commercial use of group housing systems for lactating sows is limited, but the recent transition ... more Commercial use of group housing systems for lactating sows is limited, but the recent transition to group housing during gestation in the EU may result in a renewed interest in such systems. Therefore, this review aims to identify key factors that may contribute to the success or failure of group housing of lactating sows in comparison with individual housing by describing the variety in group housing systems and discussing animal behaviour and performance compared with individual housing. Group housing systems can be divided in multi-suckling (MS) systems, in which sows are grouped with their litters, and get-away (GA) systems, which include a separate communal area accessible to sows only. These systems differ in many aspects regarding management and layout but, compared with individual housing, generally provide more environmental complexity, more freedom of movement for the sows and more freedom to express behaviours related to, for example, maternal care and social interactions...
In gilts, seminal plasma treatment before or during the LH-surge has been found to advance ovulat... more In gilts, seminal plasma treatment before or during the LH-surge has been found to advance ovulation in all animals by as much as 8 to 14 h. Two experiments were performed to assess whether such an advancement occurs in multiparous sows in which ovulation is induced by 750 i.u. hCG at 68 h after weaning. In both experiments, seminal plasma was inseminated at 4, 5 and 6 h after hCG (7 and 6 sows, respectively) and control sows (6 and 6 sows, respectively) were not inseminated. In Experiment 1, using Meishan semen, all sows ovulated between 38 and 44 h after hCG; no advancement of ovulation was seen due to treatment. In Experiment 2, using GY seminal plasma, 3 and 4 sows, respectively had started ovulation at 44 h after hCG. Again, no advancement of ovulation was seen due to treatment. Therefore, in both experiments, seminal plasma treatment within 4-6 h after hCG failed to advance ovulation to a similar extent as found in spontaneously ovulating gilts. It is unclear what causes this lack of effect. Maybe seminal plasma treatment does not advance hCG-induced ovulation or batches of seminal plasma differ in their ovulation-advancing properties.
This study assessed pulsatile release of LH during altrenogest treatment after weaning in primipa... more This study assessed pulsatile release of LH during altrenogest treatment after weaning in primiparous sows and related this to follicle development, estrus and ovulation rate. Weaned sows (n=10) received altrenogest 20mg/day from D-1 to D13 (weaning=D0) at 0800 h. On D13, blood samples were collected every 12 min from 1000 until 1900 h (1st sampling period) and from 2300 h until 0800 h (2nd sampling period). During the 1st sampling period, LH concentrations remained low and no LH pulses were detected in 8/10 sows. During the 2nd sampling period, average and basal LH concentrations (P&lt;0.04) and frequency of pulses (P&lt;0.0001) were higher than during the 1st sampling period. Sows with short vs. long intervals to estrus (&lt;5 days vs. ≥5 days) had higher basal and average LH concentrations during the 2nd sampling period (P≤0.004) and showed more follicular growth during treatment (P=0.007), generating larger follicles at D14 (P=0.005). Sows with high ovulation rate (≥25) displayed more LH pulses in total than sows with low (&lt;25) ovulation rates (P=0.03). In conclusion, this study showed that altrenogest efficiently prevented LH pulsatility during the first bleeding period and that low frequency/high amplitude LH pulses were generally present during the second bleeding period. This variability in LH release in between two altrenogest administrations (24h) may explain why follicular growth progresses to 5mm during altrenogest treatments. LH pulsatility was related to length of the follicular phase and ovulation rate, which signifies its relevance.
The timing of oestrus, the concentrations of oestradiol, LH and progesterone, and embryo survival... more The timing of oestrus, the concentrations of oestradiol, LH and progesterone, and embryo survival on day 35 of pregnancy in 16 weaned multiparous sows were studied in relation to the moment of ovulation. Ovulation was detected using transrectal ultrasonography. The interval between weaning and ovulation varied between 126 and 214 h (156 \ m=+-\ 29). The peak oestradiol concentration was 27 \ m=+-\17 pg ml\m=-\1; sows with a shorter interval between weaning and ovulation had higher peaks of oestradiol (r = \m=-\0.54, P = 0.02). The interval between the peak oestradiol concentration and peak LH concentration was 11 \ m=+-\ 4 h. The shape, width and height of the LH surge were variable, but did not influence the interval between the peak LH concentration and ovulation, which varied between 26 and 34 h (30 \ m=+-\ 3). The interval between ovulation and the time when the progesterone concentration rose to more than 1.0 ng ml\m=-\1above basal progesterone concentrations varied from 6 to 19 h (13 \ m=+-\ 4). Ovulation took place at a more or less constant relative time of the oestrous period (after 72 \ m=+-\ 8% of the duration of oestrus), irrespective of the duration of oestrus. The timing of the peak concentrations of oestradiol and LH and the rise in progesterone concentrations were closely related to the occurrence of ovulation but not to the onset of oestrus. Embryo survival on day 35 of pregnancy was related to the interval between the peak concentrations of oestradiol and LH (r = \m=-\0.68, P = 0.02); shorter intervals resulted in higher embryo survival. A similar relationship was found between embryo survival and the interval between the peak oestradiol concentration and the rise in progesterone concentration (r = \m=-\0.59; P = 0.05), and between embryo survival and the interval between the peak LH concentration and ovulation (r = 0.60; P = 0.03). In conclusion, the interval between the peak LH concentration and ovulation was on average 30 \ m=+-\ 3 h and was relatively constant between sows (from 26 to 34 h). The concentrations and temporal changes in oestradiol, LH and progesterone profiles differed among sows. The temporal relationships between hormonal changes and ovulation seem to be of importance for embryo survival and require further investigation.
Commercial use of group housing systems for lactating sows is limited, but the recent transition ... more Commercial use of group housing systems for lactating sows is limited, but the recent transition to group housing during gestation in the EU may result in a renewed interest in such systems. Therefore, this review aims to identify key factors that may contribute to the success or failure of group housing of lactating sows in comparison with individual housing by describing the variety in group housing systems and discussing animal behaviour and performance compared with individual housing. Group housing systems can be divided in multi-suckling (MS) systems, in which sows are grouped with their litters, and get-away (GA) systems, which include a separate communal area accessible to sows only. These systems differ in many aspects regarding management and layout but, compared with individual housing, generally provide more environmental complexity, more freedom of movement for the sows and more freedom to express behaviours related to, for example, maternal care and social interactions...
Commercial use of group housing systems for lactating sows is limited, but the recent transition ... more Commercial use of group housing systems for lactating sows is limited, but the recent transition to group housing during gestation in the EU may result in a renewed interest in such systems. Therefore, this review aims to identify key factors that may contribute to the success or failure of group housing of lactating sows in comparison with individual housing by describing the variety in group housing systems and discussing animal behaviour and performance compared with individual housing. Group housing systems can be divided in multi-suckling (MS) systems, in which sows are grouped with their litters, and get-away (GA) systems, which include a separate communal area accessible to sows only. These systems differ in many aspects regarding management and layout but, compared with individual housing, generally provide more environmental complexity, more freedom of movement for the sows and more freedom to express behaviours related to, for example, maternal care and social interactions. Group housing poses several risks, such as disrupted nursing and an increased level of crushing during the MS phase, and in the GA systems there is a risk for early cessation of nursing. On the other hand, pre-weaning mingling of litters clearly benefits piglet social development and may improve adaptation to the post-weaning situation. In addition, group-housed sows may show lactational ovulation, which provides opportunities for insemination during an extended lactation period, which benefits the piglets. Gradual transitions in social and physical environment around gestation, farrowing, grouping and weaning seem to be key success factors for group housing systems during lactation. In addition, selection of suitable sows and quality of stockmanship seem important.
In large organic litters, relationships between piglet birth weight, piglet uniformity and pre-we... more In large organic litters, relationships between piglet birth weight, piglet uniformity and pre-weaning piglet mortality were studied. Furthermore, effects of parity and insulin-stimulating diets during the pre-mating period on piglet birth weight, uniformity, and mortality were investigated. Organically kept sows (n = 137 sow cycles) were fed a control diet during lactation and weaning-to-insemination interval (CON), or an insulin-stimulating diet
Our objective was to study reproductive consequences of lactation bodyweight loss occurring in pr... more Our objective was to study reproductive consequences of lactation bodyweight loss occurring in primiparous sows with mild feed restriction and to relate these lactation weight losses and its consequences to metabolic profiles during lactation and subsequent early gestation. After weaning, 47 first-litter sows were retrospectively assigned to a high– (HWL, >13.8%, n = 24) or low (LWL, ≤13.8%, n =
ABSTRACT De lactatie en de periode vlak na spenen zijn belangrijke fases in het leven van zeugen ... more ABSTRACT De lactatie en de periode vlak na spenen zijn belangrijke fases in het leven van zeugen en biggen. Recent onderzoek aan ondermeer Wageningen UR geeft aanknopingspunten om deze periodes soepeler te laten verlopen voor de zeug en haar biggen
The aim of the study was to measure the effect of creep feeding during lactation on net absorptio... more The aim of the study was to measure the effect of creep feeding during lactation on net absorption in the small intestine at 4 days after weaning. Intermittent suckling was used to increase creep feed intake during lactation. Creep feed containing chromic oxide was provided. Based on the colour of the faeces, piglets were classified as 'eaters' or 'non-eaters', respectively. At day 4 after weaning, an in vivo small intestine segment perfusion test was performed at 5 sites along the small intestine in 24 piglets (12 eaters and 12 non-eaters). At both sides of each intestinal segment a tube was fitted to perfuse and drain fluid in order to assess net absorption. Net absorption was higher in eaters than in non-eaters (P b 0.001). Net absorption varied greatly between and within piglets and was highest in the caudal segments of the small intestine (P b 0.001). These data suggest that creep feeding could be a useful tool in the prevention of post-weaning diarrhoea.
Selection for litter size may result in an increase in uterine crowding due to a faster increase ... more Selection for litter size may result in an increase in uterine crowding due to a faster increase in ovulation rate than in litter size. Increased ovulation rate does not result in a proportionally increased number of piglets born alive. In this study, the effect of ovulation rate on vitality characteristics of fetal-placental units at d 40 of pregnancy was investigated. For this, 43 Large White gilts were treated with hormones to induce superovulation. Average ovulation rate was 45.16 ± 13.22; average number of vital fetuses at d 40 of pregnancy was 17.09 ± 3.61 that weighed 11.26 ± 1.99 g; their placenta weighed 31.88 ± 14.79 g; and they occupied 11.69 ± 4.90 cm of the uterus. Loss in oocytes (i.e., that did not result in a vital fetus at d 40) increased with increasing ovulation rate and occurred before (early mortality; P = 0.0003) and after implantation (late mortality, i.e., traces visible at d 40; P < 0.0001). With respect to the vital fetuses, increased ovulation rate resulted in decreased fetal (P = 0.0008) and placental weight (P = 0.0008) and decreased length of the area in the uterus that was occupied by the placenta (P = 0.0011). Strong correlations existed between placental and fetal weight [0.68; 95% confidence interval (CI) = 0.64 to 0.72], and placental weight and length (0.78; 95% CI = 0.74 to 0.82). Fetal-placental characteristics were weakly correlated to distance to the implantation sites of neighboring fetuses, a measure of crowdedness [−0.002 (95% CI = −0.042 to 0.038) with fetal weight to 0.16 (95% CI = 0.12 to 0.20) with placental length]. Increased ovulation rates, but more specifically increased late mortality rates, have negative effects on the remaining vital fetuses with respect to the fetal (P = 0.0085) and placental weight (P < 0.0001) and length of the implantation site (P = 0.0016). The most extreme effect was on placental weight, in which a uterus with <10 cases of late mortality was on average 25% greater than placental weight in a uterus with >18 cases of late mortality (P < 0.0001). Furthermore, increased ovulation rates resulted in decreased within litter variation for fetal (P = 0.0018) and placental weight (P = 0.0084). At increased ovulation rates, the number of live fetuses remained similar, but placental development is impaired and the growth of the fetus is retarded compared with reduced ovulation rate, with effects likely lasting into adult life.
Piglet birth weight and litter uniformity were studied in sows of different parities and crossbre... more Piglet birth weight and litter uniformity were studied in sows of different parities and crossbred lines in relation to: 1) weaning-to-pregnancy interval (WPI) and 2) sow body condition changes (in BW and backfat thickness) during lactation and gestation in sows with a short WPI (≤7d). At the Institute for Pig Genetics (IPG) research farm, individual piglet birth weights and sow body condition (BW and backfat thickness at farrowing and weaning) were measured for 949 TOPIGS20 and 889 TOPIGS40 sows with &amp;amp;gt;4 total born piglets, inseminated between 2003 and 2011. In all analyses, mean piglet birth weight and birth weight SD and CV were corrected for total number born. Total number born was greater in sows with a WPI of 8 to 21 d (+1.2 piglets; n = 72) and &amp;amp;gt;21 d (+0.7 piglets; n = 182), compared with sows with a WPI ≤7 d (P &amp;amp;lt; 0.01; n = 1,584). Mean piglet birth weight was not affected by WPI. Birth weight SD (-23 g) and CV (-1.7%) were lower in sows with a WPI &amp;amp;gt;21 d, compared with sows with a WPI ≤7 d (P &amp;amp;lt; 0.01). Effects of WPI were independent of sow parity. Effects of body condition changes in sows with a WPI ≤7 d were studied separately in TOPIGS20 sows inseminated between 2006 and 2011 (n = 808), and in TOPIGS40 sows inseminated between 2003 and 2008 (n = 747). Sow body condition loss during lactation was not related with subsequent total number born or mean piglet birth weight. Only in TOPIGS20 sows, more BW loss during lactation was related with greater subsequent birth weight SD (β = 0.83 g/kg, P &amp;amp;lt; 0.01; β = 1.62 g/%, P &amp;amp;lt; 0.01). Additionally, more backfat loss during lactation was related with greater subsequent birth weight SD (β = 5.11 g/mm, P &amp;amp;lt; 0.01) and CV (β = 0.36%/mm, P &amp;amp;lt; 0.01), independent of sow parity. Sow BW increase during gestation was negatively related with total number born [TOPIGS20: β = -0.06 and -0.05 piglet/kg BW increase for parity 2 (P &amp;amp;lt; 0.01), and 3 and 4 (P &amp;amp;lt; 0.01), respectively; TOPIGS40: β = -0.04 piglet/kg BW increase (P &amp;amp;lt; 0.01), independent of sow parity]. Sow BW increase during gestation was positively related with birth weight SD [TOPIGS20: β = 0.63 g/kg BW increase (P = 0.01), independent of sow parity]. Sow body condition increase during gestation was not related with mean piglet birth weight. To conclude, this study shows that litter uniformity is compromised by severe sow body condition loss during lactation and improved in sows with a prolonged WPI. These effects are likely related with (insufficient) restoration of follicle development.
Commercial use of group housing systems for lactating sows is limited, but the recent transition ... more Commercial use of group housing systems for lactating sows is limited, but the recent transition to group housing during gestation in the EU may result in a renewed interest in such systems. Therefore, this review aims to identify key factors that may contribute to the success or failure of group housing of lactating sows in comparison with individual housing by describing the variety in group housing systems and discussing animal behaviour and performance compared with individual housing. Group housing systems can be divided in multi-suckling (MS) systems, in which sows are grouped with their litters, and get-away (GA) systems, which include a separate communal area accessible to sows only. These systems differ in many aspects regarding management and layout but, compared with individual housing, generally provide more environmental complexity, more freedom of movement for the sows and more freedom to express behaviours related to, for example, maternal care and social interactions...
In gilts, seminal plasma treatment before or during the LH-surge has been found to advance ovulat... more In gilts, seminal plasma treatment before or during the LH-surge has been found to advance ovulation in all animals by as much as 8 to 14 h. Two experiments were performed to assess whether such an advancement occurs in multiparous sows in which ovulation is induced by 750 i.u. hCG at 68 h after weaning. In both experiments, seminal plasma was inseminated at 4, 5 and 6 h after hCG (7 and 6 sows, respectively) and control sows (6 and 6 sows, respectively) were not inseminated. In Experiment 1, using Meishan semen, all sows ovulated between 38 and 44 h after hCG; no advancement of ovulation was seen due to treatment. In Experiment 2, using GY seminal plasma, 3 and 4 sows, respectively had started ovulation at 44 h after hCG. Again, no advancement of ovulation was seen due to treatment. Therefore, in both experiments, seminal plasma treatment within 4-6 h after hCG failed to advance ovulation to a similar extent as found in spontaneously ovulating gilts. It is unclear what causes this lack of effect. Maybe seminal plasma treatment does not advance hCG-induced ovulation or batches of seminal plasma differ in their ovulation-advancing properties.
This study assessed pulsatile release of LH during altrenogest treatment after weaning in primipa... more This study assessed pulsatile release of LH during altrenogest treatment after weaning in primiparous sows and related this to follicle development, estrus and ovulation rate. Weaned sows (n=10) received altrenogest 20mg/day from D-1 to D13 (weaning=D0) at 0800 h. On D13, blood samples were collected every 12 min from 1000 until 1900 h (1st sampling period) and from 2300 h until 0800 h (2nd sampling period). During the 1st sampling period, LH concentrations remained low and no LH pulses were detected in 8/10 sows. During the 2nd sampling period, average and basal LH concentrations (P&lt;0.04) and frequency of pulses (P&lt;0.0001) were higher than during the 1st sampling period. Sows with short vs. long intervals to estrus (&lt;5 days vs. ≥5 days) had higher basal and average LH concentrations during the 2nd sampling period (P≤0.004) and showed more follicular growth during treatment (P=0.007), generating larger follicles at D14 (P=0.005). Sows with high ovulation rate (≥25) displayed more LH pulses in total than sows with low (&lt;25) ovulation rates (P=0.03). In conclusion, this study showed that altrenogest efficiently prevented LH pulsatility during the first bleeding period and that low frequency/high amplitude LH pulses were generally present during the second bleeding period. This variability in LH release in between two altrenogest administrations (24h) may explain why follicular growth progresses to 5mm during altrenogest treatments. LH pulsatility was related to length of the follicular phase and ovulation rate, which signifies its relevance.
The timing of oestrus, the concentrations of oestradiol, LH and progesterone, and embryo survival... more The timing of oestrus, the concentrations of oestradiol, LH and progesterone, and embryo survival on day 35 of pregnancy in 16 weaned multiparous sows were studied in relation to the moment of ovulation. Ovulation was detected using transrectal ultrasonography. The interval between weaning and ovulation varied between 126 and 214 h (156 \ m=+-\ 29). The peak oestradiol concentration was 27 \ m=+-\17 pg ml\m=-\1; sows with a shorter interval between weaning and ovulation had higher peaks of oestradiol (r = \m=-\0.54, P = 0.02). The interval between the peak oestradiol concentration and peak LH concentration was 11 \ m=+-\ 4 h. The shape, width and height of the LH surge were variable, but did not influence the interval between the peak LH concentration and ovulation, which varied between 26 and 34 h (30 \ m=+-\ 3). The interval between ovulation and the time when the progesterone concentration rose to more than 1.0 ng ml\m=-\1above basal progesterone concentrations varied from 6 to 19 h (13 \ m=+-\ 4). Ovulation took place at a more or less constant relative time of the oestrous period (after 72 \ m=+-\ 8% of the duration of oestrus), irrespective of the duration of oestrus. The timing of the peak concentrations of oestradiol and LH and the rise in progesterone concentrations were closely related to the occurrence of ovulation but not to the onset of oestrus. Embryo survival on day 35 of pregnancy was related to the interval between the peak concentrations of oestradiol and LH (r = \m=-\0.68, P = 0.02); shorter intervals resulted in higher embryo survival. A similar relationship was found between embryo survival and the interval between the peak oestradiol concentration and the rise in progesterone concentration (r = \m=-\0.59; P = 0.05), and between embryo survival and the interval between the peak LH concentration and ovulation (r = 0.60; P = 0.03). In conclusion, the interval between the peak LH concentration and ovulation was on average 30 \ m=+-\ 3 h and was relatively constant between sows (from 26 to 34 h). The concentrations and temporal changes in oestradiol, LH and progesterone profiles differed among sows. The temporal relationships between hormonal changes and ovulation seem to be of importance for embryo survival and require further investigation.
Commercial use of group housing systems for lactating sows is limited, but the recent transition ... more Commercial use of group housing systems for lactating sows is limited, but the recent transition to group housing during gestation in the EU may result in a renewed interest in such systems. Therefore, this review aims to identify key factors that may contribute to the success or failure of group housing of lactating sows in comparison with individual housing by describing the variety in group housing systems and discussing animal behaviour and performance compared with individual housing. Group housing systems can be divided in multi-suckling (MS) systems, in which sows are grouped with their litters, and get-away (GA) systems, which include a separate communal area accessible to sows only. These systems differ in many aspects regarding management and layout but, compared with individual housing, generally provide more environmental complexity, more freedom of movement for the sows and more freedom to express behaviours related to, for example, maternal care and social interactions...
Commercial use of group housing systems for lactating sows is limited, but the recent transition ... more Commercial use of group housing systems for lactating sows is limited, but the recent transition to group housing during gestation in the EU may result in a renewed interest in such systems. Therefore, this review aims to identify key factors that may contribute to the success or failure of group housing of lactating sows in comparison with individual housing by describing the variety in group housing systems and discussing animal behaviour and performance compared with individual housing. Group housing systems can be divided in multi-suckling (MS) systems, in which sows are grouped with their litters, and get-away (GA) systems, which include a separate communal area accessible to sows only. These systems differ in many aspects regarding management and layout but, compared with individual housing, generally provide more environmental complexity, more freedom of movement for the sows and more freedom to express behaviours related to, for example, maternal care and social interactions. Group housing poses several risks, such as disrupted nursing and an increased level of crushing during the MS phase, and in the GA systems there is a risk for early cessation of nursing. On the other hand, pre-weaning mingling of litters clearly benefits piglet social development and may improve adaptation to the post-weaning situation. In addition, group-housed sows may show lactational ovulation, which provides opportunities for insemination during an extended lactation period, which benefits the piglets. Gradual transitions in social and physical environment around gestation, farrowing, grouping and weaning seem to be key success factors for group housing systems during lactation. In addition, selection of suitable sows and quality of stockmanship seem important.
In large organic litters, relationships between piglet birth weight, piglet uniformity and pre-we... more In large organic litters, relationships between piglet birth weight, piglet uniformity and pre-weaning piglet mortality were studied. Furthermore, effects of parity and insulin-stimulating diets during the pre-mating period on piglet birth weight, uniformity, and mortality were investigated. Organically kept sows (n = 137 sow cycles) were fed a control diet during lactation and weaning-to-insemination interval (CON), or an insulin-stimulating diet
Our objective was to study reproductive consequences of lactation bodyweight loss occurring in pr... more Our objective was to study reproductive consequences of lactation bodyweight loss occurring in primiparous sows with mild feed restriction and to relate these lactation weight losses and its consequences to metabolic profiles during lactation and subsequent early gestation. After weaning, 47 first-litter sows were retrospectively assigned to a high– (HWL, >13.8%, n = 24) or low (LWL, ≤13.8%, n =
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