INVESTIGATING PIGLET CRUSHING BY THE SOW: A DATA MINING APPROACH

Farrowing crates represent approximately 88 % of the pig farrowing systems in the U.S. (USDA`s NAHMS, 2006). This farrowing system is very advantageous for production efficiency and management; however, it presents several pig welfare issues that are subject to concern. Generally, alternatives to farrowing crates provide a little more flexibility to the sows to communicate better with their litters, as well as to perform more exercise, posture changes, and more natural behaviors during lactation. A major concern with the alternative farrowing systems is the higher pre-wean mortality, especially due to piglet overlay. High pre-wean mortality rates impact not only the producer`s profitability, but also the welfare of young piglets. Several studies demonstrate a high variability of crushing rate among sows submitted to the same physical environment. It is possible that factors other than the system’s physical configuration may be affecting the maternal behavior of sows and causing increased crushing. Therefore, the objective of this study was to investigate how environmental and management factors affect piglet crushing, as well as the duration and frequency of sow postures and posture changes

The Effect of Triptorelin on Ovulation Rate and Conception Rate in Gilts and the Endocrine Profile in Non-Pregnant and Early pregnant Gilts

Triptorelin is a gonadotropin releasing hormone agonist that has been shown to be effective in weaned sow single fixed time artificial insemination protocols. Administration of triptorelin 96 h after weaning has been shown to be effective in synchronizing sows to be inseminated one time 24 h later without reducing pregnancy rate or the number of pigs born. In the current experiment, 23 crossbred gilts (249 d, 123 kg) were administered an intramuscular injection of PG600. Nine days after PG600 administration, gilts were fed 15 mg of altrenogest once daily for 16 d. Twelve gilts (OVU) were administered 200 μg triptorelin 96 h after the last altrenogest feeding. A single artificial insemination was then performed regardless the expression of estrus 126 h after the last altrenogest feeding. Eleven gilts (CON) were inseminated upon the expression of standing estrus and received a second insemination 24 h later. Blood was collected on d 0 (day of triptorelin administration), 1, and 2 after the administration of triptorelin for the measurement of serum concentrations of estrogen and progesterone by RIA. Estrus detection was performed daily beginning 3 d following the last altrenogest administration and ended 7 d after the last altrenogest administration. Gilts were slaughtered on d 33 when reproductive tracts were collected. Reproductive tracts were evaluated for the number of fetuses in the uterus and the number of CL on the ovary. No differences (P \u3e0.05) were found in pregnancy rate, number of fetuses, number of CL, and the ratio of fetuses to CL in all animals. When non-pregnant gilts were removed from the analysis there was a trend (P=0.08) for the CON group to have a greater ratio of fetuses to CL. Expression of standing estrus was also greater (P\u3c 0.05) in the CON group than OVU group. No differences (P \u3e0.05) were found in serum concentrations of estrogen between OVU and CON gilts. The CON group’s expression of estrus occurred around the time when progesterone was at the lowest in the group. The OVU had its lowest serum concentration of progesterone earlier than CON group. This may indicate that the OVU group could have ovulated earlier than the CON group. Data from the first experiment has demonstrated that even though conception rates of fixed timed AI protocols involving GnRH agonists are similar to standard AI, the conception rate versus ovulation rate may show differences in the two protocols. When comparing the ovulation rate with conception rate, our experiment has shown that GnRH agonists, accompanied by a single fixed timed AI, may not be effective in maximizing the number of conceptuses in gilts. Many of the gilts in this experiment failed to become pregnant even though standing estrus was exhibited in the CON group. Anterior pituitary and blood samples from these gilts were collected to determine serum concentrations of insulin like growth factor (IGF) and luteinizing hormone. Anterior pituitaries were also used to determine the expression of IGF receptor, gonadotropin releasing hormone (GnRH) receptor, luteinizing hormone beta (LH-β), IGF binding protein -2, 3, and 5. Anterior pituitaries and serum samples were collected from 15 pregnant and 8 non-pregnant gilts on d 33 after AI. Serum concentrations of estradiol and progesterone and AP concentrations of LH and IGF-1 were determined by RIA. Relative expression of GnRHR, LH-β, IGF-1, IGFBP-2, IGFBP-3, and IGFBP-5 were determined using real time reverse transcriptase PCR. Fold changes in relative expression were determined using the Relative Expression Software Tool. Non-pregnant gilts were assumed to be undergoing the luteal phase of their reproductive cycle. Our data supported this because no differences (P \u3e0.05) were determined in serum concentrations of progesterone or estradiol between non-pregnant and pregnant gilts. Mean AP concentrations of LH were greater (P0.05) between pregnant and nonpregnant gilts. Mean relative expression of LH-β was .8 fold lower (P\u3c 0.05) and IGFBP- 2 tended to be 0.8 fold lower (P=0.095) in pregnant gilts compared to non-pregnant gilts. No differences were found (P \u3e0.05) between pregnant and non-pregnant gilts in relative expression of AP GnRHR, IGF-1, IGFBP-3, and IGFBP-5. Data from the second experiment have shown that changes in multiple endocrine factors, such as LH and the IGF system, may play a crucial part in maintaining early pregnancy but further investigation is needed

Translational Genomics For Improving Sow Fertility

Sow fertility traits, such as litter size and number of lifetime parities produced (reproductive longevity), are economically important. Selection for these traits is difficult because they are lowly heritable, polygenic, sex-limited, and express late in life. Age at puberty is an early indicator of reproductive longevity. Gilts that achieve puberty at an early age have a greater probability to produce more parities over their lifetime. However, measuring age at puberty is time consuming and tedious. Identifying pleiotropic polymorphisms that affect age at puberty and other fertility traits, including reproductive longevity, could help to improve the accuracy of genomic prediction for sow fertility traits. We developed a custom Affymetrix SNP array (SowPro90) including SNPs located in major QTL regions for age at puberty, other fertility and disease related traits, and potential loss of function SNPs. Genetic variants were identified using deep transcriptomic and genomic sequencing, gene network analysis, and genome-wide association (GWAS) carried out at University of Nebraska-Lincoln (UNL) and US Meat Animal Research Center (USMARC). This novel SNP array was used to fine map the genetic sources associated with fertility traits. Using a Bayesian haplotype approach (BayesIM), SowPro90 haplotypes were inferred and assigned to the entire UNL population and were used in an association analysis for age at puberty and other fertility traits. Five major QTL regions located on four chromosomes (SSC2, SSC7, SSC14, SSC18) were discovered for age at puberty. As expected, a negative correlation (r = −0.96 to −0.10; PP2RX3, OAS1, NR2F2, PTPN11). These SNPs showed significant or suggestive effects on age at puberty, reproductive longevity, and litter size traits in the UNL population and litter size traits in the commercial sows. It will be beneficial to further characterize these SNPs and candidate genes to understand their impact on protein sequence and function, gene expression, splicing process, and how these changes affect phenotypic variation of fertility traits. Advisor: Daniel Cioban

THE DEVELOPMENT OF UNRESTRICTED, GROUP FARROWING SYSTEMS FOR SOWS

This thesis examines the activities of four groups of four sows, allocated to one of two space allocations, in a novel farrowing system design, over parturition and during lactation. The two pen configurations provided 13.4m² (L) and 8.6m² (S) per sow, respectively. A lactation diet providing 14MJ/kg DE and 18% CP was supplied ad libitum via a sow operated feeder, adapted to facilitate the calculation of individual feed intakes. The influence of environmental, physical, management and production factors upon the way in which sows allocated their time to different activities, suckling behaviour, feed intakes and feeding and drinking strategies was investigated. Sows in the small pen area were generally less active than those housed in the large pen configuration. During the first week of lactation, significantly more time was spent lying down (P<0.05) and fewer transitions were made between postures (P<0.001) in the reduced space allocation. Sows in the S pen configuration suckled their piglets significantly more frequently than sows in the L pen area (P<0.001). However, similar daily piglet weight gains were achieved in both the L and S pen configurations. Daily feed intakes of 7.69 kg (s.e. 0.31) and 7.72 kg (s.e. 0.35) were achieved during lactation, by sows in the L and S pen configurations, respectively. This was accomplished by sows taking a series of small feeds throughout the day. Sows in the S pen area made fewer visits to the feeder and spent less time per day feeding, compared with sows in the L pen area. However, more feed was consumed per visit by the S sows, resulting in similar daily feed intakes in both treatment groups. A marked increase in activity during the 24 hours prior to parturition was followed by a sharp reduction during day 1 of lactation in both treatment groups. Thereafter, activity levels increased gradually during week 1 of lactation. Most piglet deaths occurred in early lactation, 65.0% and 67.9% of which were during days 1 to 3 following birth in the L and S pen areas, respectively. Mortality of live-born piglets was unacceptably high at 19.6% in the L and 24.6% in the S pen areas. The relative advantages and disadvantages to sows and piglets within the novel farrowing system are considered in the general discussion