John W. Mabry

Factors associated with sow stayability in 6 genotypes.

The purpose of this study was to determine the association of production factors with stayability to parity 4 (STAY4) under controlled experimental conditions. Data were from 2,293 female pigs, sampled from 6 genetic lines that were entered into the National Pork Producers Council Maternal Line National Genetic Evaluation Program. Genetic lines evaluated included Newsham (NH), National Swine Registry (NSR), American Diamond Swine Genetics (ADSG), Danbred (DAN), and 2 Dekalb-Monsanto lines (DK44 and GPK347). Stepwise logistic regression was utilized in the analysis of STAY4. All effects were nested within genetic line. Categorical effects in the model were arrival date to the wean-to-finish unit (entry date) and breed-gestation-farrowing facility (farm). Continuous effects in the model were gilt backfat, LM depth, ADG, age at puberty, age at first farrowing, and traits recorded before the last litter of the sow (prefarrow backfat, number born alive, number weaned, litter weaning weight, lactation feed intake, lactation backfat loss, and lactation length). Factors significant for STAY4 included farm, entry date, age at first farrowing, ADG, gilt backfat, and lactation before removal effects, as well as feed intake, number born alive, and lactation length. Age at first farrowing and lactation feed intake affected all genetic lines. Regression coefficients for STAY4 on age at first farrowing were -0.014, -0.022, -0.017, -0.016, -0.011, and -0.021 (all P < 0.05), respectively, for NH, NSR, ADSG, DK44, GPK347, and DAN genetic lines. Regression coefficients for STAY4 on lactation feed intake were 0.043, 0.049, 0.051, 0.061, 0.120, and 0.097 (all P < 0.05), respectively, for NH, NSR, ADSG, DK44, GPK347, and DAN females. Age at puberty, age at first farrowing, and lactation feed intake had the greatest effect on STAY4.

Evaluation of current reasons for removal of sows from commercial farms.

Sow longevity is a large and often overlooked component of profitability and efficiency for commercial swine operations. Culling and mortality rates average near 50 and 9%, respectively, leaving the responsibility of profitability on sows that can remain productive past parity 3. A new study was conducted using 2,000 commercial sows, with one-half of the females being gilts and the remaining half consisting of sows that produced at least 5 litters in the same breeding herd. Although culling reasons for young sows have not changed, this study revealed the primary reason that sows over parity 5 were being culled was because of old age, regardless of their production. Sows from the parity 5 and older group had a greater number of pigs born alive through 3 parities (P < 0.05) and had a reduced wean-to-first-service interval (P < 0.05) after their first parity when compared with the females that had just entered the farm at the inception of the study. Comparisons within the young group revealed that sows that were removed from production after a single litter were inferior for the number of pigs born alive (P < 0.05) and wean-to-first-service interval (P < 0.05) compared with sows that remained in the herd for 4 parities. This study revealed that sows can be selected for longevity without detrimental effects on reproductive performance, because sows that remained in production to more advanced parities also reproductively outperformed their contemporaries that were removed early from the breeding herd.

Identification of genetic markers for productive life in commercial sows

Escalating replacement rates and production costs warrant attention on sow productive life (SPL). Increasing average SPL by one-tenth of 1 parity would result in an annual revenue increase of over

Total cost estimation for implementing genome-enabled selection in a multi-level swine production system

15 million in the United States. Research in model organisms has revealed conserved genes and gene pathways that lead to longer lifespan. The most prominent gene pathways are those involved in growth, most notably genes in the IGF pathway that serve to mimic the response of caloric restriction. The objective of this research was to test the hypothesis that these well conserved genes and gene pathways could also play a role in SPL, even though the productive life of sows is both a measure of longevity and their reproductive performance. Preliminary research on 3 distinct populations of over 2,000 animals suggested that several genes were associated with components of SPL. Genetic markers were then analyzed against the corresponding records of the sows for reproductive and longevity traits using a validation population of 2,000 commercial females. Right censored data were used to test associations of genetic markers with survival to defined time points. Three distinct models of survival analysis were implemented using nonparametric estimates of the survival distribution in a sequential order, using a parametric accelerated failure time model with a Weibull distribution of the error term, and a Cox proportional hazards model, which is a semiparametric model that uses an unspecified baseline hazard function. The genetic markers CCR7 and CPT1A were significantly associated (P < 0.05) with survival using the nonparametric model and tended (P < 0.1) toward significance using the parametric and semiparametric models with significantly different effects (P < 0.05) between some genotype classes. Genetic markers for MBL2, IGFBP3, and WARS2 also tended (P < 0.1) toward significance for survival traits, but were not consistent. Mixed model analyses were used to determine the associations of these genetic markers with reproductive traits. The genetic markers for IGFBP1, MBL2, CPT1A, CCR7, SLC22A5, and ACE were significantly (P < 0.05) associated with at least 1 reproductive trait. These results show that molecular markers should be considered for use in marker-assisted selection to improve SPL.

Evaluation of growth, deposition of back fat, and loin muscle for purebred Berkshire pigs housed in bedded hoop buildings

BackgroundDetermining an animal’s genetic merit using genomic information can improve estimated breeding value (EBV) accuracy; however, the magnitude of the accuracy improvement must be large enough to recover the costs associated with implementing genome-enabled selection. One way to reduce costs is to genotype nucleus herd selection candidates using a low-density chip and to use high-density chip genotyping for animals that are used as parents in the nucleus breeding herd. The objective of this study was to develop a tool to estimate the cost structure associated with incorporating genome-enabled selection into multi-level commercial breeding programs.ResultsFor the purpose of this deterministic study, it was assumed that a commercial pig is created from a terminal line sire and a dam that is a cross between two maternal lines. It was also assumed that all male and female selection candidates from the 1000 sow maternal line nucleus herds were genotyped at low density and all animals used for breeding at high density. With the assumptions used in this analysis, it was estimated that genome-enabled selection costs for a maternal line would be approximately US

Lean and Fat Deposition Measurements for Purebred Berkshire Pigs Housed in Hoop Barns in Iowa

0.082 per weaned pig in the commercial production system. A total of US

Relationship between Litters Per Sow Per Year Breeding Value and Sire Progeny Means for Farrowing Rate

0.164 per weaned pig is needed to incorporate genome-enabled selection into the two maternal lines. Similarly, for a 600 sow terminal line nucleus herd and genotyping only male selection candidates with the low-density panel, the cost per weaned pig in the commercial herd was estimated to be US

Assessment of the economic impact of porcine reproductive and respiratory syndrome on swine production in the United States

0.044. This means that US

Genetic parameters and trends for litter traits in U.S. Yorkshire, Duroc, Hampshire, and Landrace pigs.

0.21 per weaned pig produced at the commercial level and sired by boars obtained from the nucleus herd breeding program needs to be added to the genetic merit value in order to break even on the additional cost required when genome-enabled selection is used in both maternal lines and the terminal line.ConclusionsBy modifying the input values, such as herd size and genotyping strategy, a flexible spreadsheet tool developed from this work can be used to estimate the additional costs associated with genome-enabled selection. This tool will aid breeders in estimating the economic viability of incorporating genome-enabled selection into their specific breeding program.

Genetic parameters and trends for lean growth rate and its components in U.S. Yorkshire, Duroc, Hampshire, and Landrace pigs

This study was conducted to evaluate the accretion of BW, back fat, and loin muscle from purebred Berkshire pigs raised in bedded hoop barns in Iowa. The growth of a total of 144 purebred Berkshire pigs (18 barrows and 18 gilts per trial) was evaluated from 4 trials (2 winter and 2 summer trials). Pigs were fed ad libitum utilizing a 5-phase standard corn-soybean meal feeding program that met or exceeded NRC nutrient requirements. Pigs were housed in bedded hoop barns (unheated) to approximate common niche market requirements. At 21-d intervals, pigs were serially weighed, and ultrasonic back fat depth and loin muscle area (LMA) measurements were taken. Live BW measurements began at the trial initiation at approximately 18 to 32 kg, but ultrasonic scans for 10th-rib back fat depth and LMA began at between 36 and 45 kg until market weight of about 122 ± 2.5 kg. The rate (µ) of live body growth (weight) and ultrasonic back fat depth were influenced ( < 0.01) by trial and sex, with no significant interactions between trial and sex. Both live BW and back fat deposition were significantly greater in trial 1 than all other trials (2, 3, and 4). The rate of accretion and maximum growth of LMA depth were not affected ( > 0.05) by trial and sex. Overall, barrows averaged 31 mm of back fat at 125 kg, whereas gilts had an average of about 23 mm at 121 kg of market weight. Results suggest that because of the sex differences in growth and back fat deposition between Berkshire barrows and gilts, it may be important to formulate their diets differently in commercial pork production systems.