Herd Production Groups Research Articles

Genetic parameters for fertility traits assessed in herds divergent in milk energy output in Holstein-Friesian, Brown Swiss, and Simmental cattle

In this study, we aimed to investigate differences in the genetics of fertility traits (heritability of traits and correlations between traits in divergent environments) in dairy cows of different production levels defined on the basis of the herd-average daily milk energy output (herd-dMEO). Data were obtained from Holstein-Friesian (n = 37,359 for fertility traits, 381,334 for dMEO), Brown Swiss (n = 79,638 for fertility traits, 665,697 for dMEO), and Simmental cows (n = 63,048 for fertility traits, 448,445 for dMEO) reared in northeastern Italy. Fertility traits under study were interval from calving to first service, interval from first service to conception, days open, calving interval, calving rate, and nonreturn rate at d 56. We classified herds into low and high productivity based on the herd-average dMEO (inferred using mixed effects models). We estimated genetic parameters using Bayesian bivariate animal models, where expressions of a phenotype in the low and high dMEO herds were taken as being different-albeit correlated-traits. Fertility traits were more favorable in Simmental than in Holstein-Friesian cows, whereas for all traits, Holstein-Friesian had the highest estimates of intraherd heritability [ranging from 0.021 (0.006-0.038) to 0.126 (0.10-0.15)] and Simmental the lowest [ranging from 0.008 (0.001-0.017) to 0.101 (0.08-0.12)]. The genetic correlations between fertility traits and dMEO were moderate and unfavorable, ranging, in absolute values, from 0.527 (0.37-0.68) to 0.619 (0.50-0.73) in Holstein-Friesian; from 0.339 (0.20-0.47) to 0.556 (0.45-0.66) in Brown Swiss; and from 0.340 (0.10-0.60) to 0.475 (0.33-0.61) in Simmental cattle. The only exception was the nonreturn rate at d 56, which had weak genetic correlations with dMEO in all 3 breeds. The herd correlations between fertility and dMEO tended to be modest and favorable and the residual correlations modest and variable. The heritability of fertility traits tended to be greater in the low dMEO than in the high dMEO herds in the case of the Holstein-Friesians, but not in the case of the Brown Swiss or Simmentals. The additive genetic correlations between fertility traits in the low and high dMEO herds were always lower than 1 [0.329 (-0.17 to 0.85) to 0.934 (0.86 to 0.99)] for all traits considered in all breeds. The correlation was particularly low for the threshold characters and the interval from first service to conception in Holstein-Friesian, suggesting that the relative performances of genotypes vary significantly between herds of different dMEO levels. Although there was large variability in the estimates, results might support making separate genetic evaluations of fertility in the different herd production groups. Our results also indicate that Simmental, a dual-purpose breed, has higher fertility and lower environmental sensitivity than Holstein-Friesian, with Brown Swiss being intermediate.

Increased age at first-mating interacting with herd size or herd productivity decreases longevity and lifetime reproductive efficiency of sows in breeding herds

BackgroundOur objectives were to characterize sow life and herd-life performance and examine two-way interactions between age at first-mating (AFM) and either herd size or herd productivity groups for the performance of sows. Data contained 146,140 sows in 143 Spanish herds. Sow life days is defined as the number of days from birth to removal, whereas the herd-life days is from AFM date to removal date. Herds were categorized into two herd size groups and two productivity groups based on the respective 75th percentiles of farm means of herd size and the number of piglets weaned per sows per year: large (> 1017 sows) or small-to-mid herds (< 1017 sows), and high productivity (> 26.5 piglets) or ordinary herds (< 26.5 piglets). A two-level liner mixed-effects model was applied to examine AFM, herd size groups, productivity groups and their interactions for sow life or herd-life performance.ResultsNo differences were found between either herd size or herd productivity groups for AFM or the number of parity at removal. However, late AFM was associated with decreased removal parity, herd-life days, herd-life piglets born alive and herd-life annualized piglets weaned, as well as with increased sow life days and herd-life nonproductive days (P < 0.05). Also, significant two-way interactions between AFM and both herd size and productivity groups were found for longevity, prolificacy, fertility and reproductive efficiency of sows. For example, as AFM increased from 190 to 370 days, sows in large herds decreased herd-life days by 156 days, whereas for sows in small-to-mid herds the decrease was only 42 days. Also, for the same AFM increase, sows in large herds had 5 fewer sow life annualized piglets weaned, whereas for sows in small-to-mid herds this sow reproductive efficiency measure was only decreased by 3.5 piglets. Additionally, for ordinary herds, sows in large herds had more herd-life annualized piglets weaned than those in small-to-mid herds (P < 0.05), but no such association was found for high productivity herds (P > 0.10).ConclusionWe recommend decreasing the number of late AFM sows in the herd and also recommend improving longevity and lifetime efficiency of individual sows.

Number of pigs born alive in parity 1 sows associated with lifetime performance and removal hazard in high- or low-performing herds in Japan

Reproductive performance, lifetime performance and removal hazard were studied in commercial herds in order to detect prolific sows at an early-stage. Reproductive performance measurements that we assessed were number of pigs born alive (PBA) per litter, weaning-to-first-mating interval and farrowing rate (FR). Lifetime performance measurements included lifetime average PBA and lifetime average nonproductive days. In total, 213,514 parity records and 47,024 lifetime records of 96 herds were included. Sows were categorized into three groups based on the lower and upper 25th percentiles of PBA in parity 1:8 pigs or fewer, 9–12 pigs and 13 pigs or more. The herds were classified into high- and low-performing herds on the basis of the 50th percentile of pigs weaned per mated female per year. To compare the measurements between the sow groups taking account for the herd productivity groups, multivariate and single response models were applied to reproductive performance from first-farrowing and lifetime performance, respectively. A hazard model was fitted to survival data. Sows having 13 or more PBA in parity 1 had 1.0–1.4 more PBA per litter in all subsequent parities (P<0.05), 1.2–1.5% higher FR in parities 2–4 (P<0.05) and 3.4–3.7 higher lifetime average PBA than sows having 8 or lower PBA (P<0.01). However, there were no differences between the sow groups for weaning-to-first-mating interval in any parity (P>0.05). There were two-way interactions between the sow and herd groups for FR in parity 2 (P=0.01) and lifetime average nonproductive days (P=0.046). In low-performing herds, sows having 13 or more PBA in parity 1 had 3.9% higher FR at their next farrowings than sows having 8 or fewer PBA (P<0.05), although no such difference was found for high-performing herds (P>0.05). Sows in the low-performing herds with 13 or more PBA in parity 1 also had 2.3 fewer lifetime average nonproductive days than sows having 8 or fewer PBA (P=0.01), although again no similar difference was found for high-performing herds (P=0.96). The removal hazards for sows having 13 or more PBA in parity 1 were lower than those for sows having 8 or fewer PBA (P<0.01), with no difference in hazards between the herd groups (P=0.62). In conclusion, PBA in parity 1 may help predict a prolific sow or low PBA sow.

Delayed age of gilts at first mating associated with photoperiod and number of hot days in humid subtropical areas

The objective of the present study was to quantify the associations between age at first mating (AFM) in gilts and the climatic factors of photoperiod (PP; h), number of hot days (HD) and relative humidity for different herd productivity groups. This study used records of 37,362 gilts born in 2007 and 2008 in 101 Japanese herds, which were classified into high-performing and ordinary herds based on the pigs weaned per mated female per year. The climate data were obtained from 21 weather stations. The HD was defined as the number of days that achieved a maximum temperature >25°C. Average values of daily PP, relative humidity and HD from day 91 to 150 after birth of a gilt were coordinated with the respective gilt performance data. Two-level mixed-effects models were applied to the data by using a herd at level 2 and a gilt at level 1. Mean AFM (ranges), PP, HD and relative humidity were 247.9 days old (152–364 days old), 12.2h (9–15h), 18.7 days (0–60 days) and 68.4% (48–87%), respectively. Delayed AFM was associated with decreased PP, more HD and being in an ordinary herd (P<0.05), but not with relative humidity. As PP rose by an hour, the AFM in high-performing herds decreased by 1.13 days rather than that in ordinary herds. It is possible that AFM in replacement gilts could be hastened by improving light control and cooling management during hot days.

Quantitative associations between outdoor climate data and weaning-to-first-mating interval or adjusted 21-day litter weights during summer in Japanese swine breeding herds

The objective of the present study was to quantify the associations between climate data and either weaning-to-first-mating interval (WMI) or adjusted 21-day litter weights of sows during summer for different herd productivity groups. This study was conducted using 87,428 parity records of 61,558 sows farrowed between June and September in 2007, 2008 and 2009, in 103 Japanese herds mostly located in humid subtropical areas. The 103 herds were classified into high-performing herds and ordinary herds by the basis of the upper 25th percentile of pigs weaned per mated female per year, averaged over the three years. The climate data were obtained from 21 weather stations of the Japan Meteorological Agency. Average values of the daily maximum temperatures (HT), average daily relative humidity (RH) and temperature-humidity index (THI) for 21 days after the farrowing date of a sow were coordinated with sow performance data from a recording system. Two-level mixed-effects models were applied to the data by using a herd at level 2 and an individual record at level 1. Mean values (ranges) of HT, RH and THI were 27.8°C (17.3–36.0°C), 74.6% (57.3–90.9%) and 22.2°C (13.0–27.4°C), respectively. Higher HT, RH and THI were associated with higher WMI and lighter adjusted 21-day litter weights (P<0.05). High-performing herds had lower WMI and heavier adjusted 21-day litter weights than ordinary herds at any HT, RH and THI (P<0.05). The WMI of sows in high-performing herds did not increase as much as those in ordinary herds when HT or THI increased. For example, as HT increased from 25 to 35°C, WMI of sows in high-performing herds increased by 0.3 days, whereas those in ordinary herds increased by 0.8 days. Also, when HT, RH or THI increased, parity 1 sows showed greater increase in WMI than parity 2 or higher sows (P<0.05). For instance, as THI increased from 15 to 25°C, WMI in parity 1 sows increased by 0.9 days, whereas those in parity 2 or higher sows increased by only 0.3 days. In conclusion, high-performing herds alleviate the negative effects of humid subtropical summer climates on WMI or adjusted 21-day litter weight more than ordinary herds. The parity 1 sows were more sensitive to such summer changes in climate than parity 2 or higher sows. Therefore, it is recommended in particular for parity 1 sows that producers practice cooling management during summer.

A herd management survey on culling guidelines and actual culling practices in three herd groups based on reproductive productivity in Japanese commercial swine herds1

The objective of the present study was to investigate culling guidelines for gilts and sows in Japanese commercial herds and to compare differences between culling guidelines and actual culling practices in different herd productivity groups. A questionnaire survey was undertaken to obtain information on culling guidelines in 115 commercial swine herds that participated in the PigCHAMP data-share program. The questionnaire included questions on guideline values for culling intervals and the number of conception failure occurrences that would trigger a culling decision to be made. Ninety-two of the 115 herds (80.0%) returned appropriate data for the study and were included in the present study. In addition to questionnaire data, culling data regarding the actual culling intervals and number of reservices for gilts and sows culled during 2007 to 2008 were also obtained for the same herds from a PigCHAMP database. Culled gilts and sows were divided into 4 female groups on the basis of the stages of their reproductive life when they were culled: unmated gilts, mated gilts, unmated sows, and mated sows. Culling intervals in unmated gilts and sows were defined as the number of days from birth or weaning to culling, respectively, whereas in mated gilts and sows culling intervals were the number of days from last service to culling. Three herd productivity groups were formed on the basis of the upper and lower 25th percentiles of pigs weaned mated female(-1)·yr(-1):high-,intermediate- or low-performing herds. For unmated gilts and sows actual culling intervals were 15 d shorter than the guideline culling intervals in the surveyed data submitted by producers (P < 0.05). This shorter actual culling period for unmated gilts and sows did not vary significantly between herd productivity groups in any parity. However, for mated gilts and sows the actual culling intervals were at least 30 d longer than the guideline culling intervals (P < 0.05). Guideline and actual culling intervals for mated gilts and sows were at least 10 d shorter in high-performing herds than in low-performing herds (P < 0.05). High-performing herds had lower proportions of sows culled after the second reservice than intermediate- or low-performing herds in parity groups 0 to 5 (P < 0.05). In conclusion, culling guidelines for mated sows differed between herd productivity groups, and culling guidelines for mated gilts and sows were not strictly followed in any herd group in the commercial herds.

国内養豚生産農場における夏季の高気温及び湿度と繁殖成績との定量的関連性

The objective of this study was to quantify the associations between summer climate data and reproductive performance of sows in lactation by herd productivity groups and by parity in Japanese commercial herds. This study was conducted by using 56,779 parity records of 45,506 sows farrowed between June and September in 2007 and 2008 in 113 herds. The climate data included records of daily maximum temperatures and daily relative humidity reported in 21 weather stations of Japan Meteorological Agency. Average values of the maximum temperatures (maximum temperatures) and relative humidity (relative humidity) for 21 days from the farrowing for individual sows were coordinated with reproductive data of the sows. The 113 herds were classified into high-, intermediate- and low-performing herds on the basis of pigs weaned per mated female per year. Parity records of sows at farrowing were classified into two groups:1 and 2 or higher. Two-level analysis was applied using a herd at level 2 and an individual record at level 1. Means (±SEM) of maximum temperatures and relative humidity during summer from 2007 to 2008 were 28.1±0.01°C and 74.2±0.02%, respectively. Increased maximum temperatures during summer were associated with prolonged weaning-to-first-mating interval (WMI), lower farrowing percentage and fewer subsequent pigs born alive (subsequent PBA; P<0.05). Increased relative humidity were associated with prolonged WMI (P<0.05), but not with farrowing percentage and subsequent PBA (P0.05). There were two two-way interactions between maximum temperatures and herd productivity groups or parity for WMI (P<0.05). As maximum temperatures increased by 1°C, WMI of sows in high-performing herds increased by 0.08 days, whereas those in low-performing herds increased by 0.21 days. As maximum temperatures increased by 1°C, WMI in parity 1 and 2 or higher sows increased by 0.16 days and 0.10 days, respectively. A two-way interaction between relative humidity and parity was found (P<0.05). In parity 1 sows, WMI increased by 0.10 days as relative humidity increased by 1%, whereas WMI in parity 2 or higher sows did not increase. A two-way interaction between the maximum temperatures and parity was found for farrowing percentage (P<0.05). A parity 1 sow lactating at 30°C of the maximum temperatures was 0.95 times as likely to farrow as a sow lactating at 25°C. Meanwhile, a parity 2 or higher sow lactating at 30°C was 0.98 times as likely to farrow as a sow lactating at 25°C. There was a two-way interaction between maximum temperatures and herd productivity groups for subsequent PBA (P<0.05). As maximum temperatures increased by 1°C, subsequent PBA of sows in high-performing herds decreased by 0.06 pigs, whereas subsequent PBA of sows in low-performing herds decreased by 0.09 pigs. In conclusion, this study indicates that negative effects of high temperatures during lactation on WMI and subsequent PBA are different between herd productivity groups. Additionally, it is harder in parity 1 sows than parity 2 or higher sows that negative effects of high temperatures or relative humidity during lactation on WMI and farrowing percentage.

Swine Herds Achieve High Performance by Culling Low Lifetime Efficiency Sows in Early Parity

Sow lifetime performance and by-parity performance were analyzed using a 3 by 3 factorial design, comprising 3 herd productivity groups and 3 sow efficiency groups. Data was obtained from 101 Japanese herds, totaling 173,526 parity records of 34,929 sows, for the years 2001 to 2006. Sows were categorized into 3 groups based on the lower and upper 25th percentiles of the annualized lifetime pigs born alive: low lifetime efficiency sows (LE sows), intermediate lifetime efficiency sows or high lifetime efficiency sows. Herds were grouped on the basis of the upper and lower 25th percentiles of pigs weaned per mated female per year, averaged over 6 years: high-, intermediate- or low-performing herds. Mixed-effects models were used for comparisons. LE sows in high-performing herds had 57.8 fewer lifetime nonproductive days and 0.5 earlier parity at removal than those in low-performing herds (P<0.05). The number of pigs born alive of LE sows continuously decreased from parity 1 to 5, whereas those of high lifetime efficiency sows gradually increased from parity 1 to 4 before decreasing up to parity ≥ 6 (P<0.05). In conclusion, the LE sows have a performance pattern of decreasing number of pigs born alive across parity. The present study also indicates that high-performing herds culled potential LE sows earlier than the other herds.

On the Estimation of Variances Within Herd-Mean Production Groups

In investigating heterogeneity of variance among herd groups, herds are often grouped according to their mean production, and variances are estimated within such groups using a sire model. Stratifying herds in this way may be a form of “selection” on sire progeny groups, resulting in herd production groups with a selected sample of sires, causing a “pseudoheterogeneity” of variance to be estimated. A selection effect was not found for balanced nested and cross-classified designs, For a balanced design, the only biased estimate of the sire variance is obtained for the limited case of selection directly on progeny group means, with the absence of any fixed effects other than a mean. For unbalanced designs, the bias depends on the distribution of regressions of progeny means on herd means and is likely to be negligible in most practical analyses in which there is substantial variation within herds due to environmental effects.

Detection of Heterogeneous Variance in Herd Production Groups

The detection of heterogeneous variance across herd groups is based largely on data stratified by mean herd production. Such stratification is analogous to selection on herd means. This introduces the possibility of biased estimates of genetic and residual variances. Results presented show that Henderson's Method 3 estimates of the residual variance are unbiased by selection on herd means. However, reductions in sums of squares for sires have different expected values in no selection and selection models. The magnitude of this bias is evaluated with a small-scale simulation. Extension of these results to other methods of variance estimation reveals a potential bias from selection on herd means.

Trends in Genetic and Phenotypic Variances for Milk Production

Residual standard deviations estimated separately for each year of first freshening from first lactation milk records of artificially sired Holstein cows increased from 1960 to 1982, especially after 1976. The pattern on the square root scale was similar. On the logarithmic scale, residual standard deviations were smallest in the middle of the time period. Heritabilities estimated from paternal half-sib correlations were greater than .30 on all scales until about 1976 when estimates began to go below .20. Estimates were similar for untransformed and transformed records. When records were divided into four herd production groups within each year, the same patterns over time for residual standard deviations were observed as for the combined data for each year. On the untransformed scale, the largest standard deviations were associated with high herd production and the smallest with low herd production. On the square root scale, standard deviations were similar for all herd production groups. On the log scale, residual standard deviations were smallest with high production and largest with low production—the reverse of the untransformed scale, although differences were smaller. Heritability was highest with middle-production groups and smallest with low-production groups. Data available for each year ranged from 1,400 and 2,849 to 6,821 and 58,082 records, respectively, of daughters of sampling and proved bulls with from 115 to 513 sampling bulls.