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The objectives of this study were to measure death intervals and survival, to determine mortality rate and mortality risks, and to investigate the association of herd factors with mortality risk in individual female pigs. This study was conducted by obtaining female data with lifetime records of 65,621 females born between 1999 and 2002, and herd data with mean measurements of 5 yr from 2000 to 2004 in 105 herds. Annualized mortality rate was calculated as the number of dead females divided by the sum of life days in all gilts and sows, multiplied by 365 d. Mortality risk was calculated as the number of dead females divided by the number of surviving females at farrowing in each parity. Death interval in gilts was defined as the number of days from birth to death, and that in sows was the number of days from the last farrowing to death. A Cox proportional hazards model was used to obtain the survival probability by parity. Logistic regression analyses were used to investigate the association of herd factors with mortality risk in individual females in each parity. Of the 65,621 females, the mortality risk was 9.9%, and the annualized mortality rate was 3.9%. Of the 6,501 dead females, death intervals in gilts and sows were 294.7 and 55.0 d, respectively. In gilts, survival probability rapidly decreased at 33 and 50 wk of age, around the first mating and the first parturition. In contrast, survival probability in sows decreased at wk 1 after farrowing, and rapidly decreased at wk 20 and 21 after farrowing in all parity groups that were around a subsequent peripartum period. The percentages of death on wk 0, 1, and 2 after the last farrowing in all the dead sows were 6.5, 23.5, and 10.1%, respectively. Approximately 10% of deaths also occurred from wk 20 to 21 after the last farrowing. Death interval in parity [greater than or equal to] 5 was the shortest among all parity groups (49.2 d; P < 0.05). Mortality risks in parities 0 and 1 were 1.44 and 1.83%, respectively. As parity increased from 2 to [greater than or equal to] 5, mortality risk increased from 1.63 to 5.90%. Herd factors (greater herd mortality, less herd productivity, and smaller herd size) were associated with greater mortality risk in individual females in parity 0 to [greater than or equal to] 5, parity 4 and [greater than or equal to] 5, and parity 1 to 4, respectively (P < 0.05). In conclusion, females in peripartum periods, gilts, and high-parity sows are at a greater risk of dying. Increased care should be implemented for prefarrowing females and early-lactating SOWS. Key words: death, management, mortality, sow, survival, well-being

The objectives of this study were to determine changes in herd productivity and the performance of female pigs over time in commercial swine herds. Annual measurement data from 1999 to 2003 were obtained from the record files of 113 herds in Japan. Two groups were formed according to the 25th percentile of pigs weaned/mated females per year (PWMFY) in 2003; the 2 groups were high-performing herds (those constituting the top 25%) and the remaining ordinary herds. The effects of group based on PWMFY in 2003, year, and the group x year interaction on repeated measures between 1999 and 2003 were analyzed by using mixed-effects models. A regression analysis was also used to compare key measurements in productivity between the 2 groups, with years as a continuous variable. Variance components were obtained to determine herd repeatability of PWMFY for the 2 herd groups. The average female inventory in creased from 290 [+ or -] 31 to 355 [+ or -] 42 females for these 5 yr. The PWMFY also changed from 20.9 [+ or -] 0.21 to 21.2 [+ or -] 0.30 pigs. An interaction between year and group was detected (P < 0.05) for PWMFY. In the regression comparison, high-performing herds increased their PWMFY by 0.31 [+ or -] 0.09 pigs each year, whereas the ordinary herds did not increase. The number of pigs weaned per sow increased by 0.07 [+ or -] 0.02 pigs each year in high-performing herds and increased by 0.03 [+ or -] 0.01 pigs each year in ordinary herds. In high-performing herds, for each year, the percentage of sows mated by 7 d after weaning increased by 0.92 [+ or -] 0.25%, the percentage of reserviced females decreased by 0.63 [+ or -] 0.26%, and culling rate increased by 1.53 [+ or -] 0.50%. Repeatability of PWMFY for high-performing herds and ordinary herds was 28.8 and 54.0%, respectively. This study shows that productivity in high-performing herds was improved compared with that of ordinary herds. Key words: commercial farm, herd repeatability, management, pig, repeated measure

Annual performance measurements, age structures of female pig inventories, and by-parity culling rates were abstracted from data files of 110 herds that participated in a data-share program in Japan. Parity at culling was used as a prime measurement of longevity, whereas pigs weaned*mated [female.sup.-1]*[year.sup.-1] (PWMFY) was a prime measurement of reproductive efficiency. High or low longevity herds were based on the greatest 50% of the herds or the remaining herds ranked by parity at culling, whereas high or low reproductive efficiency herds were grouped according to the greatest 50% of the herds or the remaining herds ranked by PWMFY. Measurements were analyzed as a 2 x 2 factorial arrangement, using the main effects of the 2 herd groups of longevity (high or low) and reproductive efficiency (high or low). Means of parity at culling and PWMFY were 4.6 (SD = 0.82) and 21.2 (SD = 3.02), respectively. The high longevity group had 1.27 greater parities at culling than the low longevity group (P < 0.05), but no differences between the high and low longevity groups were found in PWMFY (P = 0.21). No differences between the high and low efficiency groups were found in parity at culling (P = 0.50). No interactions between the longevity and efficiency groups were found on any longevity or efficiency measurement (P > 0.20). In herd management, the percentage of reserviced females and the percentage of multiple matings were associated with the longevity group and the efficiency group (P < 0.05). The high longevity group had lower culling rates in parity 0 to 6 than the low longevity group (P < 0.05), whereas no differences between the low and high efficiency groups were found in culling rates in parity 0 to 2 (P > 0.20). This study suggests that measures to achieve longevity and high reproductive efficiency in breeding herds do not conflict and that high reproductive efficiency and high longevity can be achieved. Key words: management, reproductive productivity, sow longevity, welfare

Of 105 swine herds using a production record system for breeding female pigs, 95 farms were used to analyze nonproductive female days (NPD), the six component intervals of NPD, and related measurements. The NPD was defined as the days when mated gilts and sows were neither gestating nor lactating, and it was calculated by summing the six component intervals in the average mated female inventory. The mean NPD was 57.9 d (SD = 20.5), and the proportions of six component intervals of gilt first-mating-to-pregnancy interval, gilt first-mating-to-culling interval, unmated weaning-to-culling interval, weaning-to-first-mating interval, sow first-mating-to-pregnancy interval, and sow first-mating-to-culling interval were 9.24, 7.82, 6.85, 27.9, 18.9, and 29.3c2, respectively. Farms in the upper 25th percentile of the ranking for number of pigs weaned x mated [female.sup.-1] x [yr.sup.-1] were designated as 25 high-performing farms. The remaining farms were designated as an ordinary farm group for comparisons. High-performing farms had 21.1 d fewer NPD, and five of the six component intervals were lower compared with the ordinary farms (P < 0.05). Regression analyses indicated that the number of litters x mated [female.sup.-1] x [yr.sup.-1] increased by 0.07 in both farm groups as NPD decreased every 10 d. Fewer NPD were correlated with a higher percentage of multiple matings during estrus (P < 0.05) but were not correlated with removal risk and replacement risk in both farm groups. The average parity of culled females was negatively correlated with NPD in the ordinary farm group, and the average farrowed parity was positively correlated with NPD in the high-performing farm group (P < 0.01). Decreasing each component interval of the NPD six components is critical to increasing herd productivity. A high percentage of multiple matings during estrus and appropriate culling management may be key factors to decrease NPD. Key Words: Management, Nonproductive Female Days, Pigs, Reproductive Efficiency, Sow Productivity

The behavior of stalled females pigs was observed to investigate the relations between behavior and reproductive performance. A commercial farrow-to-finish farm equipped with a computerized recording system with approximately 300 female pig inventories was visited three times to observe three postural behaviors (lying, standing, and sitting) and three stereotypies (vacuum chewing, drinker playing, and bar biting) of stalled females at 15-min intervals for 6 h (25 times including 0 min of one zero-time sampling) after feeding. Relative frequencies (%) of the postural behaviors and the stereotypies for 6 h were expressed as a percentage of a total of 25 time observations. Statistical models for reproductive performance included each behavior, parity, and day of visit. Among 609 pregnant females observed at our three visits, the means in relative frequencies (%) of lying, standing, sitting, vacuum chewing, drinker playing, and bar biting for 6 h were 60.1 [+ or -] 0.91, 32.3 [+ or -] 0.87, 7.60 [+ or -] 0.44, 12.7 [+ or -] 0.65, 0.4 [+ or -] 0.06, and 0.2 [+ or -] 0.50%, respectively. Among 514 farrowed females of the 609 pregnant females, the means of total pigs born, pigs born alive, pigs born dead, birth litter weights, pigs weaned, and adjusted 21-d litter weights were 12.3 [+ or -] 0.13, 11.2 [+ or -] 0.12, 1.1 [+ or -] 0.06, 17.1 [+ or -] 0.18 kg, 10.3 [+ or -] 0.08, and 68.1 [+ or -] 0.40 kg, respectively. Females showing a high relative frequency ([greater that or equal to] 36%) of vacuum chewing during gestation produced fewer (P < 0.05) total pigs born (11.7 [+ or -] 0.38 vs. 12.6 [+ or -] 0.22) than those showing no vacuum chewing. No relationships were found between vacuum chewing and other performance measurements such as pigs born alive, pigs weaned, and adjusted 21-d litter weights. Neither postural behavior nor the other stereotypies were related to reproductive performance. The farrowing rate was not related to any postural behavior and stereotypy in logistic regression mixed models. This study suggests that a subpopulation of females exists on commercial farms that frequently exhibit vacuum chewing and give birth to fewer total pigs. High frequency of vacuum chewing in those females may be indicative of their suboptimal reproductive performance. Key Words: Pigs, Stereotypies, Vacuum Chewing

Effects of three dietary lysine (protein) concentrations during lactation on metabolic state, protein metabolism, reproductive hormones, and performance were investigated in 36 primiparous sows. Sows were assigned randomly to one of three diets containing .4% (low lysine, LL), 1.0% (medium lysine, ML), or 1.6% (high lysine, HL) total lysine from intact protein sources. All diets contained 2.1 Mcal NE/kg and exceeded the recommended requirements for all other nutrients. Actual lysine intakes over an 18-d lactation were 16, 36, and 56 g/d for sows fed LL, ML, and HL, respectively. Fractional breakdown rate of muscle was determined on d 4 and 15 of lactation by using a three-compartment kinetic model of 3-methylhistidine metabolism. Increasing lysine intake during lactation did not affect fractional breakdown rate of muscle on d 4 of lactation but decreased it on d 15 (P < .05). Sows fed LL had a reduced number of LH pulses on d 12 and 18 (P < .05) and reduced serum estradiol (E(sub 2)) concentration on d 18 of lactation compared with sows fed ML and HL treatments. However, LH pulses and E(sub 2) concentrations were similar between ML and HL treatments (P > .35). Increasing lysine intake increased serum urea nitrogen (SUN) and postprandial insulin concentrations (P < .05) during lactation but had no effect on plasma glucose concentrations (P > .20). Sows fed HL had greater serum IGF-I on d 6 and 18 than sows fed ML (P < .05). Number of LH peaks was correlated with serum insulin concentration 25 min after feeding on d 6 and 18 (r = .31 to .41; P < .1) and pre- (r = .33 to .46) and postprandial (r = .30 to .58) SUN concentrations (P < .05) during different stages of lactation. Results indicate that, compared with medium lysine intake, low lysine intake increased muscle protein degradation and decreased concentrations of insulin, SUN, and estradiol and LH pulsatility. In contrast, high lysine (protein) intake increased SUN, insulin, and IGF-I, but did not increase secretion of estradiol and LH compared with medium lysine intake. Furthermore, nutritional impacts on reproduction may be mediated in part through associated effects on circulating insulin concentration. Key Words: Glucose, Insulin, Lactation, LH, Lysine, Sows

The objective of this experiment was to evaluate the influence of glucose infusion during lactation on LH secretion in the energy-restricted sow. Ten primiparous Landrace x Yorkshire sows (152 kg postfarrowing) were fed a lowenergy (6.5 Mcal of ME/d), high-lysine (45 g/d), corn-soybean meal diet throughout lactation. On d 18 of lactation, sows received a continuous infusion (i L/12 h) of glucose (50% dextrose solution) or .9% saline from 1200 to 2400. Blood samples were drawn every 15 min for an 18-h period on d 18 to evaluate concentrations of plasma glucose, serum insulin, and serum LH before (600 to 1200) and during (1215 to 2400) the infusions. The glucose infusion immediately increased (P < .001) plasma glucose and serum insulin relative to preinfusion levels. Glucose and insulin concentrations in sows receiving the glucose infusion were higher (P < .001) throughout the infusion period relative to concentrations in sows receiving a saline infusion. Glucose infusions had no influence on LH pulsatility during the 12-h infusion period. In contrast to the response observed in the nutrient-restricted gilt, these results indicate that glucose infusions do not result in an immediate increase in pulsatile LH secretion in the energy-restricted, lactating sow. Key Words: Lactating Sows, Infusion, LH, Insulin, Glucose, The effect of glucose infusion during lactation on luteinizing hormone (LH) secretion of sow feeding on a low-energy diet was investigated. Plasma glucose, serum insulin and serum LH were monitored every 15 minutes on day 18 of lactation. The results showed that glucose infusion dramatically increased plasma glucose and serum insulin levels in energy-restricted, lactating sows. In contrast with nutrient-restricted sows, glucose infusion had no effect on pulsatile LH secretion.

The objective of this study was to examine interactions between climatic factors, parity, and weaning-to-first-mating interval (WM1) for total number of pigs bom at subsequent parity (TPB) of female pigs serviced during 2 seasons. The present study analyzed records of 27,739 gilts and 127,670 parity records of sows in 95 Japanese herds; the records included females that were serviced between June and September (hot and humid season) or between December and March (cold season) in 2007 through 2009. The climate data were obtained from 20 weather stations located close to the studied herds. Mean daily maximum temperatures (Tmax), mean daily minimum temperatures (Tmin), and mean daily average relative humidity (ARH) for 21 d preservice and 15 d postservice for each female were coordinated with that female's reproductive data. Linear regression models with random intercept and slopes were applied to the data. Mean TPB (±SEM) was 11.9 ± 0.01 pigs. Mean values (ranges) of Tmax in the hot and humid season and Tmin in the cold season were 28.4 (13.6 to 39.8°C) and 2.0°C (-13.2 to 17.6°C), respectively. Also, mean ARH in the hot and humid season and the cold season were 73.2 (35 to 98%) and 65.2% (25 to 99%), respectively. In the hot and humid season, TPB in gilts decreased by 0.05 pigs for each degree Celsius increase in preservice Tmax (P < 0.05). However, there was no association between gilt TPB and either postservice Tmax (P = 0.11 ) or pre- and postservice ARH (P ≥ 0.66). In sows, as preservice Tmax increased from 25 to 30°C, TPB in parity groups 1 and 2 or higher decreased by 0.6 and 0.4 pigs, respectively (P < 0.05). Also, sow TPB decreased by 0.1 to 0.4 pigs as postservice Tmax increased from 25 to 30°C (P < 0.05). In sows with WMI of 0 to 12 d, TPB decreased by 0.2 to 0.5 pigs as pre- or postservice Tmax increased from 25 to 30°C (P < 0.05). However, in sows with WMI of 13 d or more, TPB was not associated with pre- or postservice Tmax (P ≥ 0.10). As preservice Tmax increased from 25 to 30°C, TPB in sows under 81.6% ARH (90th percentile) decreased by 0.5 pigs (P < 0.05), whereas TPB in sows under 65.7% ARH (10th percentile) decreased by only 0.3 pigs (P < 0.05). Postservice ARH in the hot and humid season was not associated with sow TPB (P = 0.18). During the cold season there was no association between TPB and pre- or postservice Tmin (P ≥ 0.09) or ARH (P ≥ 0.45). Therefore, we recommend that producers apply cooling management for females during periservice in summer to increase TPB. [ABSTRACT FROM AUTHOR]

A 4000 sow farm in the US using early weaning and a computerized record system was recruited. Farrowed sows were assigned into two experimental treatments: prostaglandin F2α injection or control. Sows were assigned by a farm worker to obtain even parity distributions between two groups in each farrowing group. A single i.m. injection of 2 ml of prostaglandin F2α between 24 and 48 h after farrowing was administered in the muscle immediately lateral to the vulva. Control sows received no treatment. Of 3562 farrowed sows, 1592 were administered with prostaglandin F2α. Parity distributions were not different between control and treatment groups. Parity was categorized into two groups: parity 1–2 or ≥3. Mean lactation length was 18 days and there was no difference between the control and treatment groups. No main effects of prostaglandin F2α administration were found in either parity group on adjusted 21-day litter weight, weaning-to-first-mating interval or weaning-to-conception interval. In parity ≥3 sows, a two-way interaction between the association of lactation length and treatment with pigs born alive at subsequent farrowing was found (P=0.044), while no such interaction was found in parity 1–2 sows (P=0.14). The prediction line for subsequent pigs born alive indicates that prostaglandin F2α administration alters the relationship between lactation length and subsequent litter size on mid- or old-parity sows. [Copyright &y& Elsevier]

Our objectives were to examine weaning-to-first-mating interval (WMI) across parities; probability of sows being mated 4 - 6 d postweaning at subsequent parity; repeatability and correlations in WMI between consecutive parities; and an association between lactation length (LL) and probability of sows being mated 4 - 6 d postweaning. An observational cohort study over 6 yr was conducted by using 94 farms containing 58,144 WMI records of 14,140 gilts born during 1999. Five groups of WMI were formed: 0 - 3, 4 - 6, 7 - 20, 21 - 27, and ≥ 28 d. Spearman rank correlation analysis was done. Variance components analysis was used to determine repeatability of the WMI groups. Mixed models were used to analyze the associations of the WMI groups and LL with the probability of sows being mated 4 - 6 d postweaning at subsequent parity. Random effects were farm, farrowing yr, the four periods of three-mo intervals, and the yr x the four periods in all models. The overall proportion of WMI 4 - 6 d group in all WMI groups was 81.8%. As parity increased from 1 to ≥ 7, the means of WMI decreased from 9.7 to 5.8 d, and the proportion of WMI 4 - 6 d increased from 67.0 to 90.4% (P < 0.05). The WMI 4 - 6 d group had the highest farrowing rate, and had greater subsequent pigs born alive than the WMI 7 - 20 d group (P < 0.05). The correlation coefficients of WMI between consecutive parities were low (0.11 ≤ r ≤ 0.18; P < 0.05). The repeatability of WMI was low (0.08). The probabilities of sows being mated 4 - 6 d postweaning at subsequent parity in the WMI 0 - 3, 4 - 6, 7 - 20, 21 - 27, and ≥ 28 d were 82.6, 88.4, 73.9, 75.6, and 69.6%, respectively. The probability of sows being mated 4 - 6 d increased from 59.8 to 83.0% as LL increased from 8 to 31 d (P < 0.05). These results indicated that sows in any WMI group were more likely to be mated 4 - 6 d postweaning at subsequent parity. Increasing LL at subsequent parity can be used for sows with prolonged WMI to increase the probability of sows being mated 4 - 6 d postweaning at subsequent parity. [ABSTRACT FROM AUTHOR]

Discusses the abstract of the study 'Behaviors in stalled pregnant females and reproductive performance on a commercial swine farm,' presented at the American Society of Animal Science's Midwestern Branch conference on March 17-19, 2003, in Des Moines, Iowa.

Increased number of services and prolonged reservice intervals (RI) lowered herd productivity. Our objectives were to observe a reservice occurrence and RI; farrowing rate and subsequent pigs born alive (PBA) by the number of services and RI; and an interaction between the number of services and parity with the reproductive performances. We used 115,731 serviced and 94,086 farrowed female pig records from 117 farms in 2002 in this study. A service was defined as one or more mating events in a 10-d time period. The number of services were categorized into three groups: first, second, and third or later-services. Six groups of RI were formed: 11 - 17, 18 - 24, 25 - 38, 39 - 45, 46 - 107, and 108 - 150 d. Farrowing rate and PBA by the number of services and the RI groups were compared using the statistical mixed models. All models included farm and mated mo as a random effect. The proportions of the serviced female pigs by first, second, and third or later-services were 88.6, 9.7, and 1.7%, respectively. Farrowing rate decreased from 83.7 to 48.4% as the number of services increased from first to third or later-services (P < 0.05). The second-service group had 0.4 or more PBA than the first-service group at parity 1 and 2 (P < 0.05). No difference in PBA was found between the number of service groups at parity 0 and ≥ 3. The mean of the RI was 44.4 ± 0.3 d. The proportions of the RI 18 - 24 and 39 - 45 d groups were 39.3 and 12.3%, respectively. As parity increased from 0 to ≥ 6, the proportions of the RI 18 - 24 d group increased from 37.6 to 44.1%, while the proportions of the RI 39 - 45 d group decreased from 13.3 to 8.9% (P < 0.05). The RI 18 - 24 d group had a lower farrowing rate than the RI 25 - 38 d group (P < 0.05), but had farrowing rates similar to the RI 11 - 17, 39 - 45, 46 - 107, and 108 - 150 d groups. No difference in PBA was found between the RI groups. In conclusion, increasing farrowing rate at first service, and minimizing the RI in reserviced females improved herd productivity. [ABSTRACT FROM AUTHOR]

Assistance to sows and piglets during farrowing and early lactation enables producers to decrease perinatal mortality. It is useful for producers to estimate gestation length (GL) and the due birth dates to farrowing in individual sows, because early inductions of parturition cause high neonatal mortality. The objectives were to observe the GL across parities; repeatability and correlation of the GL between consecutive parities; and the associations between GL and three litter size variables (total pigs born, pigs born alive, and dead piglets). An observational study over 6 yr was conducted by using 94 farms containing 67,028 farrowed records of 14,140 gilts born during 1999. Variance components analysis was used to determine repeatability of GL. Partial correlation analysis was done using total pigs born as a controlled variable. The GL was categorized into seven groups: ≤ 112, 113, 114, 115, 116, 117, and ≥ 118 d. Mixed models were used to analyze the associations between GL and the litter size variables. Random effects were farm, farrowing yr, the four periods of three-mo intervals, and the yr x the four periods. The means of GL across parities were from 115.2 to 115.4 d. The GL ranged from 105 to 125 d. The proportions of sows with GL 114, 115, and 116 d in all farrowing events were 19.2, 30.8, and 22.2%, respectively. A difference of frequency distributions of GL across parities was not found. The GL between consecutive parities from 1 to 6 were correlated (0.41 ≤ r ≤ 0.58; P < 0.05). The repeatability of GL was 0.47. Sows with GL 113 - 116 d had greater pigs born alive than those with GL ≤ 112 and ≥ 117 d (P < 0.05). Sows with GL ≤ 112 d had greater dead piglets than those with GL ≥ 113 d (P < 0.05). The GL became shorter, as total pigs born increased. Sows farrowed ≥ 14 pigs had 0.7 d shorter GL than those with ≤ 8 pigs (P < 0.05). High repeatability and correlations in the GL were found in this study. Keeping records of GL at each parity is recommended to estimate subsequent GL. [ABSTRACT FROM AUTHOR]

The objectives in this study were to study lactational performance across parities; associations between lactational performance and postweaning reproductive performance; and correlations of three lactational performances between consecutive parities. The three performances were weaning litter weight (WLWt), average pig weight at weaning (PIGWt), and number of pigs weaned (PW). This cohort study over 6 yr was conducted by using 94 farms containing 66,239 weaned records of 14,140 females born during 1999. Five groups of PW were formed on the basis of 5, 25, 75, and 95 percentiles of sows: ≤ 6, 7 - 8, 9 - 10, 11, and ≥ 12 pigs. Three groups of WLWt were formed on the basis of upper and lower 25 percentile of sows: ≤ 48.0, 48.0 - 70.0, and ≥ 70.0 kg. Pearson correlation analysis and partial correlation analysis using PW as a controlled variable were done. Mixed models were used to analyze the associations between farrowing rate, weaning-to-first-mating interval, and lactational performance. Across parities, the means of PW ranged from 8.9 to 9.7 pigs. The means of WLWt across parities ranged from 56.3 to 61.6 kg, and the heaviest WLWt was found at parity 2 and 3 (P < 0.05). The correlations were found between consecutive parities from 1 to 6 in WLWt and PIGWt (0.38 ≤ r ≤ 0.56; P < 0.05). Sows with PW ≤ 6 pigs had the longest weaning-to-first-mating intervals among the PW groups (P < 0.05). No differences in weaning-to-first-mating intervals were found in the PW ≥ 7 pigs groups. Sows with PW 9 - 10, 11, and ≥ 12 pigs had higher farrowing rates than those with PW ≤ 8 pigs (P < 0.05). Sows with WLWt ≥ 70.0 kg had the highest farrowing rate (P < 0.05), and had weaning-to-first-mating intervals similar to those with WLWt < 70.0 kg. Sows with PW 9 - 10 pigs had an approximately 100 g heavier PIGWt than those with PW 11 pigs (P < 0.05). Maximized WLWt with PW ≥ 9 pigs did not impair farrowing rates and weaning-to-first-mating intervals. High correlations in WLWt indicated that sows with heavy WLWt were more likely to be productive at subsequent parity. [ABSTRACT FROM AUTHOR]

Background: Knowing the feed intake pattern during lactation of modern genetic sows is crucial because it allows to anticipate possible problems and maximize their performance. On the other side, electronic feeders permit real-time data to be available for a more accurate evaluation of sow eating behavior. This work aimed to characterize the feed intake patterns of lactating highly prolific sows and determine their effect on reproductive performance. A database of 1,058 registers of feed intake collected from a commercial farm was used to identify five consistent sets of clusters (feeding curves) using machine learning. In the second step, the five feeding curves were characterized into five patterns by high, medium and low feed intake during 0-6 d and 7-28 d of lactation: 1-HH, 2-MH, 3-HM, 4-MM and 5-LL., Results: The mean daily feed intake of all the sows was 6.2 kg (0.06 SEM) across the 5 patterns. As the pattern numbers increased from 1-HH, 2-MH, 3-HM and 4-MM to 5-LL, their mean daily feed intake decreased from 7.6 to 6.9, 6.4, 5.8 and 4.3 (0.06 SEM) kg, respectively (P < 0.01). Sows with Pattern 1-HH tended to have shorter weaning-to-first service interval (P = 0.06) and had a higher farrowing rate than those with Pattern 5-LL (P < 0.01). Furthermore, contrast analysis showed that sows with Patterns 1-HH and 2-MH tended to have more piglets weaned (P = 0.05) and lower preweaning mortality (P = 0.07) than those with Patterns 3-HM and 4-MM. Also, sows with Patterns 1-HH and 3-HM had fewer stillborn piglets and a lower percentage of stillborn piglets and mummies than those with Patterns 2-MH and 4-MM (P < 0.01)., Conclusions: This study indicates the importance of reaching Pattern 1-HH by rapidly increasing feed intake during early lactation and high feed intake during late lactation, which is associated with high weaning performance and subsequent reproductive performance of the sows. Also, the current study suggests that Pattern 1-HH is linked to good farrowing with a low percentage of stillborn piglets and mummies. Finally, it is critical for producers to timely identify a problem of sows' eating behavior and to make a prompt decision to intervene., (© 2023. The Author(s).)