No description available.

No description available.

No description available.

Direct selection for increased litter size was practiced for eleven generations in a Large White-Landrace composite line of pigs. Litters were standardized at birth so that no replacement gilts were reared in a litter with more than ten pigs. A contemporary control line was maintained. In generation nine, the estimated mean breeding value for litter size was 0.63 pigs greater in the select than control line. The objective of this research project was to test associations between Type I markers and response to selection. A candidate gene approach was employed to search for markers, which may explain some of the difference in litter size between the two lines. Two novel markers were discovered within the follistatin gene, which have shown associations with litter traits. The estrogen receptor marker was not segregating in the population of pigs used in this study. The retinol binding protein marker was segregating in the population studied; however the magnitude of allele frequency change was relatively small. Polymorphisms were not detected in other candidates tested.

MicroRNAs are small (~19-24nt) non-coding RNAs that are involved in the regulation of gene expression. They are mainly expressed in development and many are expressed in a temporal as well as, a spatial manner. It is thought they may regulate up to 30% of all genes. Pyrosequencing using 454 Life Science technology is becoming the preferred method for microRNA profiling ad sequencing compared to the previous method of cloning and using traditional sequencing techniques. Use of 454 Life Sciences technology allows for a greater coverage of microRNAs and increases the chances of sequence low abundance microRNAs. In the current project we created four small RNA libraries from embryonic chick tissues, the spleen and liver at developmental time points E15 and E20. These libraries were then sequenced using 454 Life Sciences pyrosequencing. A total of 92,919 sequence reads were obtained, representing a total of 52,001 known chicken microRNAs. Of these 92,919 reads, 52,001 represented miRNAs matching the miRBase G. gallus database, and 3,472 were not found in the G. gallus database but were homologues of miRBase miRNAs from other species. Of these homologous reads 391 represented potential novel miRNAs. Other small RNAs, such as tRNA and rRNA, represented 24,672 of the reads, and 12,383 reads represented other types of sequences, such as degraded mRNA. More than one hundred different known miRNAs were identified in this study, and many were expressed in all four libraries. Common miRNAs that yielded multiple reads from all four libraries included miR-125b and miR-21, which are involved in general processes of cellular proliferation. Overall, the spleen libraries had a larger array of miRNAs than the liver libraries. Much of spleen development occurs during the later stages of embryonic development, so we can reasonably expect that many gene expression changes occur during these stages. As a result of this study, we identified nine potential novel chicken miRNAs. These novel miRNAs appear to be tissue-specific. The potential novel miRNAs appeared to be expressed at lower levels than some of the known miRNAs, which could indicate that most of the highly-expressed chicken miRNAs have already been identified, whereas, for the most part, the miRNAs expressed at low levels remain to be discovered.

The object of this study was to estimate repeatabilities and heritabilities of indirect measures of pig behavior. Relationships of measures of behavior with production traits were estimated. Traits chosen were backtest, resident-intruder, human approach (HAT), novel object (NOT), birth weight (BW), backfat depth (BF), loin muscle area (LMA), average daily gain in the farrowing house (ADGFH), average daily gain (ADG), 21 d weight (21DW), and 140 d weight (W). Each behavior trait was measured twice (n ≥ 457). The study consisted of 95 litters from 31 sires with an average of 3 sires per litter. Between 7 and 14 d of age the backtest was conducted by placing each pig in the supine position for 60 s. Total time spent struggling (TTS) and total number of attempts to struggle (TAS) were recorded. The resident-intruder test was performed in the nursery while the human approach (HAT) and novel object tests (NOT) were performed on the finishing floor. The resident intruder test involved two pigs; a resident pig and an intruder pig from another litter. The resident pen was divided in half with a solid door. One pig, a resident, was placed in the test area and an intruder pig was then introduced. Time taken until an attack occurred (LAT) and total number of attacks over the two tests (RIS) were recorded. Amount of time taken for each pig to make snout contact with an unfamiliar human (HAT) or object (NOT) was recorded. Dam and sire effects were significant for all traits (p < 0.01). Sex and pen effects were significant for LAT, RIS, HAT, and NOT (p < 0.10). Repeatabilities of TTS, TAS, RIS, LAT, HAT, and NOT were 0.38, 0.21, 0.07, 0.08, 0.17, 0.11, respectively. The phenotypic correlation between TTS and TAS was 0.61 and the phenotypic correlation between HAT and NOT was 0.34. The phenotypic relationship between RIS and LAT was -0.85. Total time spent struggling and TAS tended to be phenotypically correlated with 21DW and ADGFH. TAS was phenotypically correlated with BF (0.15). Latency until an attack occurred was phenotypically correlated with LMA (0.23). RIS was phenotypically correlated with ADG (-0.13), W (-0.13), and LMA (-0.21). Heritabilities of TTS and TAS were 0.31 and 0.53, respectively. Genetic correlation of TAS with both ADG and W was 0.38. Genetic correlations of TTS with BF, W, and TAS were 0.14, 0.18, and 0.81, respectively. It was concluded that the backtest is a heritable and repeatable measure of a behavioral characteristic in pigs that is both phenotypically and genetically correlated with performance.

The objective of this study was to determine effects of divergent selection for testosterone on testicular morphology and daily sperm production. Duroc boars from lines divergently selected for testosterone production in response to GnRH challenge for 10 generations followed by random selection were used. In generation 21 endogenous testosterone in the high testosterone line (H, n=54) and low testosterone line (L, n=44) averaged 490 ng/ml and 278 ng/ml (P < 0.01), respectively. Plasma FSH concentrations did not differ between lines (P < 0.3). Body weight, testicular weight, and epididymal weight were recorded for boars from H (n=82) and L (n=44) castrated at an average age of 211 d and 97 kg. Testicular tissues were sampled from animals castrated in generation 20 (H, n=46 and L, n=13). Volume densities for Leydig cells, seminiferous tubules, and Sertoli cells were estimated along with sperm production. After adjustment for body weight, average paired testicular weights for H and L were 417 g and 457 g (P < 0.01), respectively. Adjusted epididymal weights also differed between lines (P < 0.02), with H having larger epididymal weights. Line H (n=46) had greater volume densities of Leydig cells than L (n=13) (P < 0.02). Volume density of seminiferous tubules tended to differ between lines (P < 0.07), and Sertoli cell volume densities did not differ (P < 0.27). Sperm production traits, adjusted for age, did not significantly differ between lines. Selection for testosterone production in response to a GnRH challenge was an effective method of changing testosterone levels, testicular size, epididymal weight, and volume density of Leydig cells and seminiferous tubules. However, daily sperm production per gram of testes was unchanged. At this time, selection for testosterone in order to increase sperm production is not recommended.

Gastrointestinal (GI) parasitism may be the most challenging health problem associated with raising goats. Two trials were conducted to evaluate the effects of copper (Cu) oxide needles (CuON) on trichostrongylid parasites in grazing Boer-cross yearling goats. In trial 1, 18 does and 18 wethers (40 kg BW) were stratified by fecal egg counts (FEC) and sex, and sorted into 6 groups of 6 animals in a randomized complete block design (RCBD) with 3 replications. On d 0, control (CTL) goats received a combined dose of fenbendazole (10 mg/kg BW) and levamisole (11 mg/kg BW) whereas treated goats received a 5 g CuON bolus. In trial 2, 45 wethers (48 kg BW) were stratified by FEC and randomly assigned to 1 of 9 groups of 5 animals each in a RCBD with 3 replications. Treatments were 0 g (CTL), 5 g, or 10 g of a CuON bolus. In both trials, goats were rotationally grazed in separate bermudagrass/crabgrass plots. Fecal and blood samples were taken every 7 d. Liver samples and the abomasum (trial 2 only) were taken when animals were sacrificed on d 77 (trial 1) and d 59, 60 and 63 (trial 2). In trial 1, FEC were lower (P < .06) for CuON goats on d 31 (2,426 vs 4,115 eggs/g feces). Packed cell volume was higher in CTL goats on d 67 (32.2 vs 27.7%, P < .02) and d 74 (28.8 vs 24.6%, P < .03). Total protein was also higher in CTL goats on d 53 (6.6 vs 6.0 g/dL, P < .03) and d 74 (6.4 vs 5.7 g/dL, P < .01). Liver Cu concentrations were higher (P < .044) in CuON goats (395 vs 138 mg/kg DM). Liver lesions and plasma Cu concentrations did not differ. In trial 2, FEC were higher (P < .01) in CTL than 10g CuON goats on d 14 (CTL: 4117; 5 g: 2795; 10 g: 1768 eggs/g feces). Goats on 10 g CuON had lower (P < .04) PCV on d 14 (CTL: 31.3; 5 g: 32.4; 10 g: 29.1%). Liver Cu concentrations increased linearly (P < .01) (CTL: 92; 5 g: 296; 10 g: 386 mg/kg DM). Total protein, plasma Cu concentrations, liver lesions and number of Haemonchus contortus or Trichostrongylus axei found in the abomasum were similar. Although CuON have the potential to become part of an integrated internal parasite program, additional research is needed before CuON can be recommended as a safe and effective anthelmintic.

During the last half of the 20^th century, the world pork industry has achieved astonishing developments in pig breeding. Now swine farms are larger, ownership more concentrated, and farms have become more industrialized. Artificial insemination (AI) plays an important role in animal breeding increasing utilization of genetically superior sires. Currently boars selected for commercial use as AI sires are evaluated on grow-finish performance and carcass characteristics. The objectives of this study were to (A) estimate genetic correlations between production and semen traits in the boar; average daily gain (ADG), back fat thickness (BF) and muscle depth (MD) as production traits, and total sperm cells (TSC), total concentration (TC), volume collected (SV), number of extended doses (ND), and acceptance rate of ejaculates (AR) as semen traits; (B) to model the variances and covariances of total sperm cells (× 10⁹) over the active lifetime of AI boars; and (C) to compare multiple traits and random regression analyses applied to total sperm cells (TSC). Average heritability estimates were 0.39 for ADG, 0.32 for BF, 0.15 for MD, and repeatability estimates were 0.38 for SV, 0.37 for TSC, 0.09 for TC, 0.39 for ND, and 0.16 for AR. Semen traits showed negative genetic correlations with MD. Genetic correlations would indicate that current selection objectives are having a negative effect on semen traits. Therefore, current AI boar selection practices may be having a detrimental effect on semen production. In random regression analysis for total sperm cells, maximum log likelihood value was observed for sixth, fifth, and seventh order polynomials for fixed, additive genetic and permanent environmental effects, respectively. Best fit as determined by Akaike's Information Criterion was based on a model with sixth, fourth, and seventh order polynomials for fixed, additive genetic and permanent environmental effects, respectively. Best fit as determined by Schwarz Criterion was by fitting fourth, second, and seventh order polynomials for fixed, additive genetic and permanent environmental effects, respectively. Heritability estimates for total sperm cells ranged from 0.27 to 0.61 across age of boar classifications. Heritability for total sperm cells tended to increase with age of boar classification. The cyclic nature of heritability for total sperm cells that was observed over the active lifetime of boars may be due in part to number of observations across seasons limiting our ability to correct for seasonal effects on sperm production. In MTDFREML analysis, heritability estimates of 9, 12, 15, 18, 21, 24, and 27 months of age were, respectively, 0.28, 0.29, 0.26, 0.27, 0.30, 0.79, and 0.41. The results from MTDFREML seemed to be overestimated when compared to random regression. Therefore, random regression methods are the most appropriate to analyze semen traits as they are longitudinal data measured over the boars lifetime.

The objective of this study was to characterize growth, carcass composition, and meat quality in two Duroc lines of pigs divergently selected 10 generations for testosterone production and then maintained by random within line selection. In generation 21 endogenous testosterone production in the high (HTL) and low (LTL) testosterone lines averaged 49.0 ng/ml and 27.8 ng/ml (P < 0.01), respectively. Eight LTL and 10 HTL boars were used to create 29 LTL and 33 HTL litters. These same boars were mated to a line of white composite (WC) females to generate 11 WC by LTL litters (WLT) and 23 WC by HTL litters (WHT). Barrows and gilts were then selected LTL (n = 53), HTL (n = 61), WLT (n = 102), and WHT (n = 101) for testing. Pigs were weighed and scanned using real-time ultrasound 48 h prior to one of two slaughter dates. Data were analyzed with a mixed model including fixed effects of line, mating type, sex, and random effect of sire nested within line. All possible interactions among fixed effects were tested. Growth and carcass traits analyzed included days to 114 kg (D114), average daily gain (ADG), back fat adjusted to 114 kg (BF), loin muscle area adjusted to 114 kg (LMA), and predicted percent lean (PPL). Fat-O-Meater data collected included hot carcass weight (HCW), adjusted fat depth (FDEPTH), adjusted loin depth (LDEPTH) and percent lean (%LEAN). Meat quality traits characterized included marbling score at 24 h post-mortem (MAR), percent lipid (%LIPID), pH, water-holding capacity (DRIP), color score (CS) and Minolta L*, a*, and b*. The HTL had fewer D114 (P < 0.05), greater ADG (P < 0.01), greater BF (P < 0.01) and lower PPL (P < 0.01) than LTL. For crossbred progeny, WHT and WLT did not differ for D114, ADG, or BF. The WLT had larger LEA (P < 0.05) and higher PPL (P < 0.01) than WHT. The WLT had lower LDEPTH (P < 0.05) than LTL and HTL. The LTL and HTL had higher subjective scores for MAR (P < 0.05). Least square means for %LIPID for HTL and LTL were 4.00 and 3.95, respectively. The WHT had higher means for DRIP (P < 0.01), L*, a* and b* (P < 0.05) than WLT, but did not differ for pH or CS measurements. Pigs selected for increased testosterone production grew faster and produced fatter carcasses than pigs selected for decreased testosterone. Because of their high intramuscular fat content and acceptable meat quality, these lines may be useful in developing premium products.