Genetic associations for gilt growth, compositional, and structural soundness traits with sow longevity and lifetime reproductive performance.

The objective of this study was to estimate genetic associations for gilt growth, compositional, and structural soundness with sow longevity and lifetime reproduction. Performance and pedigree information from 1,447 commercial females from 2 genetic lines were included in the data analyzed. Growth was expressed as days to 113.5 kg BW (DAYS) and compositional traits included loin muscle area (LMA), 10th rib backfat (BF10), and last rib backfat (LRF). Structural soundness traits included body structure traits [length (BL), depth (BD), width (BWD), rib shape (BRS), top line (BTL), and hip structure (BHS)], leg structure traits [front legs: legs turned (FLT), buck knees (FBK), pastern posture (FPP), foot size (FFS), and uneven toes (FUT); rear legs: legs turned (RLT), leg posture (RLP), pastern posture (RPP), foot size (RFS), and uneven toes (RUT)], and overall leg action (OLA). Lifetime (LT) and removal parity (RP) were considered as longevity traits whereas lifetime reproductive traits included lifetime total number born (LNB), lifetime number born alive (LBA), number born alive per lifetime day (LBA/LT), and percentage productive days from total herd days (PD%). Genetic parameters were estimated with linear animal models using the average information REML algorithm. Second, to account for censored longevity and lifetime reproduction records, genetic parameters were estimated using Markov Chain Monte Carlo and Gibbs sampling methods. Similar estimates were obtained across the analysis methods. Heritability estimates for growth and compositional traits ranged from 0.50 to 0.70 and for structural soundness traits from 0.07 to 0.31. Longevity and lifetime reproductive trait heritability estimates ranged from 0.14 to 0.17 when REML was used. Unfavorable genetic correlations were obtained for DAYS with LT, RP, LNB, LBA, and PD% and for LRF with PD%. However, LMA was favorably associated with LT, RP, and LNB. Moderate to high correlations were obtained for BL and BRS with all longevity and lifetime reproductive traits. Correlations of BWD with LT and RP were moderate. Associations for leg soundness traits with longevity and lifetime reproductive traits were mainly low and nonsignificant (P ≥ 0.10). However, RLP was moderately correlated with LBA/LT and PD%. Current results indicate that selection for fewer DAYS has an antagonistic effect on lifetime performance. Furthermore, great BL, flat BRS, narrow BWD, and upright RLP seem detrimental to sow longevity and lifetime reproduction.

Genetic parameters for growth, body composition, and structural soundness traits in commercial gilts.

The objective of this study was to estimate genetic parameters for growth, body composition, and structural soundness traits in commercial gilt lines. The data included 1,449 gilts: 462 females from a grandparent maternal line and 987 from a parent maternal line. Growth was expressed as number of days to a constant 113.5 kg BW (DAYS) and compositional traits included loin muscle area (LMA), 10th rib backfat (BF10), and last rib backfat (LRF). Subjective structural soundness evaluation was completed using a 9-point scale and included: body length (BL), body depth (BD), body width (BWD), rib shape (BRS), top line (BTL), and hip structure (BHS); front legs: legs turned (FLT), buck knees (FBK), pastern posture (FPP), foot size (FFS), and uneven toes (FUT); rear legs: legs turned (RLT), leg posture (RLP), pastern posture (RPP), foot size (RFS), and uneven toes (RUT); and overall leg action (OLA). Genetic parameters were estimated with multivariate linear animal models, using the average information REML algorithm. Heritability estimates for growth and body composition traits ranged from 0.50 to 0.70, for body structure traits from 0.15 to 0.31, for leg structure traits from 0.07 to 0.31, and the estimate for OLA was 0.12. Several moderate to high genetic correlations were obtained among body structure traits, whereas correlations among leg structure traits were mainly low and nonsignificant. A strong correlation was found between FPP and OLA (P < 0.001); more upright FPP coincided with inferior OLA. Furthermore, FBK and FFS appeared to be favorably associated with OLA (0.05 < P < 0.10). Body structure trait correlations among each other and with leg soundness traits were primarily favorable. Correlations indicated that great BL and high BTL coincided with each other and deterioration of other structural soundness traits. Although genetic correlations obtained for DAYS and backfat measurements with structural soundness traits had an unfavorable trend, they were mainly low to moderate (i.e., simultaneous genetic improvement would be possible, including adversely associated traits). Due to greater heritabilities, faster genetic change could be expected for compositional and body structure traits than leg structure traits. Because of the genetic relationship among the trait groups, using information across traits when making selection decisions could result in genetic improvement among leg soundness traits.

Partial characterization of ovine intrauterine suppressor cells.

Ovine uterine cells that represented Day 14 cyclic and pregnant endometrium were fractionated with Percoll and evaluated for suppression of cocultured phytohemagglutinin (PHA)-induced peripheral blood lymphocyte (PBL) proliferation and for the presence of T-lymphocyte markers. Uterine cells were then evaluated for suppressor activity following the depletion of conventional lymphocyte classes (i.e., T-, B-, and NK-like) with complement + antibody treatment. In addition, supernatant (derived from cultured uterine cells) was tested for transforming growth factor beta (TGFbeta) activity using neutralization antibodies to TGFbeta. Fractionated uterine cells (density range of 1.002-1.056 g/ml) from cyclic and pregnant ewes suppressed PHA-induced proliferation of PBL, and the majority (69.5%) of these cells were < or = 5.2 microm in diameter. Percentages of CD5+, CD4+, and CD8+ lymphocytes recovered from endometrial curettage were less for cells in this density range than for cells with greater densities. Uterine cells released suppressor factor(s) into the culture medium (supernatant); however, suppressor activity was unaffected by either anti-TGFbeta or complement + antibody treatment. In conclusion, low-density uterine cells from Day 14 cyclic and pregnant ewes suppressed the proliferation of cocultured PBL and released a suppressor factor(s) into the medium that did not exhibit TGFbeta activity. It is unlikely that the suppressor cells comprise conventional T-, B-, or NK-like lymphocyte lineages.

In vitro and in vivo effects of lymphokine-activated killer cells upon preattachment ovine conceptuses.

An investigation assessed the cytolytic effect of autologous ovine lymphokine-activated killer (LAK) cells upon preattachment ovine conceptuses. For an in vitro experiment, conceptuses were recovered from six ewes on each of days 14, 16, and 19 (estrus = day 0). Dissociated conceptus cells (5 x 10(4), considered target cells) were incubated with autologous LAK cells at varying E:T ratios (5:1-200:1) and cytotoxicity was assessed by 51Cr release. In vivo, control (saline), cultured PBL (1 x 10(7)) and LAK cells (1- and 4- x 10(7)) were infused into the lumen of the uterine horn ipsilateral to the corpus luteum of mated ewes on day 14. Conceptuses were recovered on day 19 and placed within one of three morphologic categories (intact, large fragments, or highly fragmented). The numbers of mononucleated and binucleated giant cells and remaining trophoblastic cells were then quantitated within sections of conceptus tissue. Mitotic activity was also recorded. At E:T ratios of 100:1 and 200:1, respectively, percent 51Cr release for LAK cell cultures was greater (p < 0.05) for day-16 and 19- than day-14 conceptus cells. The frequencies of highly fragmented conceptuses recovered from saline + cultured PBL and LAK cell-infused ewes were 0/10 and 8/13, respectively. Within tissue sections, the numbers of morphologically normal mononucleated giant and mitotic cells were less (p < 0.05) for LAK cell (4 x 10(7)) than for saline-infused ewes. Data from additional in vitro and in vivo experiments revealed that supernatants from LAK cell (4 x 10(7)) cultures failed (p > 0.05) to affect % 51Cr release from K-562 target cells, conceptus morphology, and numbers of conceptus cells. In conclusion, autologous LAK cells exerted in vitro and in vivo lytic damage upon preattachment ovine conceptuses. A temporal pattern was observed for the in vitro lytic responses.

Temporal patterns of secretion of porcine uterine suppressor and stimulatory macromolecules.

Temporal secretory patterns of porcine uterine suppressor (>/=230 kD) and stimulatory (29 kD) macromolecules were evaluated within uterine luminal protein (ULP) secretions recovered during early pregnancy. The ULP was recovered by uterine flushing from four Landrace gilts each on Days 9, 12, 15 and 18 of pregnancy. Unfractionated and fractionated ULP (using Sephacryl S-200) was tested for suppression or stimulation of phytohemagglutinin-induced peripheral blood T-lymphocyte proliferation. For all days of pregnancy, unfractionated ULP suppressed (P<0.002 to 0.0001) lymphocyte proliferative responses, with the greatest (P<0.05) activity observed for ULP collected on Day 9 of pregnancy. Suppressor activity resulted from the >/=230 kD component, in which the activity was greater (P<0.05) for ULP from gilts on Day 9 than Days 12, 15 and 18 of pregnancy. The 29 kD component failed (P>0.05) to stimulate lymphocyte proliferation, although there was a nonsignificant stimulatory trend for 2 of 4 gilts each at Days 12 and 15 of pregnancy. These findings demonstrate a temporal secretory pattern for the >/=230 kD lymphocyte suppressor component, which may be requisite for the immunological survival of the conceptus during early pregnancy. The inconsistent appearance of the lymphocyte stimulatory factor (29 kD component) tends to minimize its biological significance relative to the immunology of pregnancy.

Interference with the cytolytic activity of interleukin-2-treated lymphocytes by bovine uterine luminal protein.

Bovine uterine luminal protein (ULP) components (> or = 4 x 10(6) and 21,000 M(r)) were obtained from uterine flushings on Day 17 of pregnancy. Experiments were conducted to determine the capability of these components to interfere with the cytolytic activity of interleukin-2 (IL-2)-treated peripheral blood lymphocytes (PBL), designated LAK (lymphokine-activated killer) cells, upon K-562 tumor cells. Proteins (10-100 micrograms) were added at the onset of a 5-day culture period to wells containing PBL (3 x 10(6) + bovine recombinant IL-2 (12,000 IU). After culture, percentage cytotoxicity (Cyt) was assessed by the 51Cr release assay at 4 and 22 h of incubation for ratios (5:1-200:1) of LAK:K-562 cells. Percentage Cyt was affected (p < 0.0001) by time, ratio, protein treatment, and all two-way interactions. Although trends were apparent, neither ULP component affected (p > 0.05) percentage Cyt at 4 h. By 22 h of incubation, mean percentage Cyt values for the > or = 4 x 10(6) and 21,000 M(r) components at effector:target cell ratios of 150:1 (p < 0.002) and 200:1 (p < 0.0001) were less than percentages for LAK cells alone. BSA and serum protein (control preparations) each failed (p > 0.05) to affect percentage Cyt. In conclusion, both ULP components interfered with the cytolytic activity of LAK cells, presumably by the suppression of LAK cell generation.

Secretion of ovine lymphocyte suppressor factor from curetted uterine luminal cells.

The secretion of ovine lymphocyte suppressor factor from jugular vein (JV), uterine vein (UV), and curetted hemopoietic uterine luminal (UL) mononuclear cells was evaluated on d 14 of the cycle, following ovariectomy (OVX) and after 14 d of progesterone injections (OVX + P4, 1 mg/kg BW). Mononuclear cells (predominantly lymphocytes) were harvested by Ficoll-Paque and placed into culture (2.5 x 10(6).mL-1.well-1 in RPMI-1640). Cellular supernatants were obtained at 72 h and volumes (5 to 50 microL) were tested for suppression of phytohemagglutinin (PHA [.08 microgram l)-treated peripheral blood lymphocytes (1.0 x 10(5)). In a concurrent experiment, PHA-treated JV, UV, and UL cells (1.0 x 10(5)) were cultured singly and JV cells (1.0 x 10(5)) were also cocultured with each of 1.0 x 10(5), 5.0 x 10(4), and 2.5 x 10(4) UV and UL cells. The incorporation of thymidine into DNA was quantified at 60 h. For the cellular supernatant experiment, thymidine incorporation was affected by reproductive phase (P less than .036), lymphocyte source (P less than .0001), and phase x source (P less than .004). For UL cells, the degree of suppressor activity follows: d 14 greater than OVX greater than OVX+P4 (P less than .05). The UL supernatant from OVX+P4-treated ewes and supernatants of JV and UV cells, irrespective of reproductive phase, lacked suppressor activity. Sephacryl S-200 chromatography revealed that UL supernatant from d-14 ewes contained a greater than or equal to 248,000 molecular weight suppressor macromolecule. For the cellular coculture experiment, thymidine incorporation was affected by reproductive phase (P less than .05) and lymphocyte source (P less than .0001).(ABSTRACT TRUNCATED AT 250 WORDS)

Endometrial T-lymphocyte subset infiltration during the ovine estrous cycle and early pregnancy.

T-lymphocytes were quantitated within luminal, stromal and glandular areas of ovine endometrium. In experiment 1, ovariectomized (OVX), estrus (E) and day 13 (D13) ewes (six/group) received 500 micrograms of phytohemagglutinin (PHA) or vehicle in ligated right and left uterine horns, respectively. At 48 h, uteri were removed for the immunohistochemical evaluation of T-lymphocyte subsets. In experiment 2, T-lymphocytes were quantitated within non-pregnant and pregnant uterine horns on day 19. For experiment 1, mean numbers of T4 and T8 lymphocytes within luminal and stromal areas of PHA-treated horns were greatest (P less than 0.05) for D13 ewes and least (P less than 0.05) for E ewes. Numbers of T6 lymphocytes for these same areas were greatest (P less than 0.05) for PHA-treated horns of OVX ewes. Overall, the T4/T8 ratio (P less than 0.004) and mean number of T19 cells (P less than 0.009) were increased by PHA. Numbers of CD45R lymphocytes were not affected by PHA but were greater (P less than 0.05) in glandular and luminal than stromal areas. For experiment 2, mean numbers of endometrial T4, T6, T8 and T19 lymphocytes were similar (P greater than 0.05) between non-pregnant and pregnant horns; however, the number of CD45R lymphocytes was greater (P less than 0.05) in endometrial tissue of pregnant than non-pregnant horns. The data indicate that the in vivo response of specific ovine T-lymphocytes to PHA was generally dependent upon reproductive stage and the presence of conceptus tissue influenced the infiltration of CD45R lymphocytes.

Suppression of interleukin-2 mediated T-lymphocyte blastogenesis by bovine uterine secretions.

Uterine luminal protein (ULP) secretions collected on day 17 of bovine pregnancy contain high (greater than or equal to 248 kDa)- and low (7, 21.0, and greater than or equal to 72 kDa)-molecular weight (Mr) components that suppressed incorporation of thymidine into both phytohemagglutinin (PHA)-stimulated and interleukin-2 (IL-2)-stimulated bovine lymphocytes. The pattern of suppressor activity for ULP was similar for both PHA and IL-2 cultures. For IL-2-treated lymphocytes (2 X 10(4)/culture well), mean percentage of control (no test protein) values for 8 and 32 micrograms/ml of high Mr ULP were 94.6% and 4.5%, respectively; whereas, mean values for 8 and 64 micrograms/ml of combined low Mr ULP components were 51.2% and 5.5%, respectively. The data indicate that specific bovine ULP components may locally affect T-lymphocyte function by altering some facet of the IL-2 activation system.

Estimation of phenotypic selection differentials for predicting genetic responses to ratio-based selection.

Ratios of the phenotypic values of two traits may be used as selection criteria in animal and plant breeding to improve the ratio traits themselves or to effect changes in their two component (numerator and denominator) traits. Prediction of genetic responses to ratio-based selection would facilitate quantitative analysis and evaluation of selection based on ratios. Methods for predicting such responses are derived and presented here. They employ expressions for the truncation value of a ratio and for the phenotypic selection differentials of the numerator and denominator traits. The derivation of these expressions is based upon the assumption that the phenotypic values of each of these traits are normally distributed. Worked examples relating to livestock and crop improvement are included to demonstrate how responses to selection for ratios may be predicted.

Immunosuppressive activity of uterine luminal protein from steroid-treated ovariectomized heifers.

Uterine luminal protein (ULP) collected from ovariectomized steroid-treated crossbred heifers was tested for immunosuppressive activity in vitro. Heifers were allotted to treatment groups and for 16 d received daily injections of the following steroids or vehicle: Control (C, corn oil only, n=10); estradiol-17beta (E(2), 1.1 mug/kg body wt, n=10); progesterone (P(4), 2.2 mg/kg body wt, n=10); and E(2)+P(4) (1.1 mug + 2.2 mg/kg body wt, n=9). On Day 17, uterine flushings were collected, concentrated and quantitated for total ULP. ULP was tested for suppression of lymphocyte blastogenesis. For each experiment, 5 x 10(5) bovine lymphocytes were incubated with 0.4 mug of phytohemagglutinin (PHA) and ULP (25 to 400 mug ULP/ml) using standard culture conditions. At 48 h, 0.5 muCi of (3H) thymidine was added to cultures with cells harvested at 60 +/- 1 h by automation. Incorporated thymidine was measured by scintillation chromatography. Mean total ULP values for C-, E(2)-, P(4)- and E(2)+P(4)-treated groups were 4.7, 8.4, 13.6, and 25.5 mg, respectively (E(2)+P(4)>C and E(2), P<0.05). ULP from all treatment groups suppressed (P<0.0001) lymphocyte blastogenesis (thymidine incorporation) to PHA; however, suppression was greater (P<0.0001) for ULP from E(2)- and P(4)-than C-treated heifers at 100 and 200 mug ULP/ml. In conclusion, E(2) and P(4) injections enhanced immunosuppressive activity of ULP secretions.

Seasonal LH profile in ovariectomized cattle.

Two experiments were conducted to examine seasonal changes in circulating LH concentrations in ovariectomized heifers. In experiment 1, four Holstein heifers were ovariectomized in April 1977 during middiestrus. Blood samples were collected daily for 30 days surrounding each equinox and solstice for one year to examine changes in plasma LH levels at the time of seasonal photoperiod changes. The LH concentrations were highest during the winter solstice period and lowest during the summer solstice period. In addition, samples taken at two-week intervals indicated a distinct LH profile with maximal LH concentrations during November-April and minimal concentrations during May-October. In experiment 2, eight Holstein heifers were ovariectomized in June-July, 1979 and given an estradiol or a control implant in October. A distinct LH profile for the interval extending from January, 1980 to February, 1981 was found in the heifers that were not treated with estradiol. Concentrations were maximal during December-April and minimal during May-November. The LH profile followed a similar pattern in the estradiol-treated heifers; however, the overall profile was at a higher level. These data indicate that underlying seasonal reproductive mechanisms are present in cattle even though the species ovulates and breeds throughout the year.

Estimating the precision of estimates of genetic parameters realized from multiple-trait selection experiments.

The genetic change from multiple-trait selection experiments can be equated to the regression of genotype on phenotype. This gives rise to a method of obtaining estimates of additive genetic variances and covariances. The method requires the use of selection weights, derived by means of the index-in-retrospect, to provide invariant solutions. Solution variance estimates obtained from Monte Carlo simulation do not agree with variance estimates from ordinary least squares methods. This indicates that the errors are distributed with some structure V. A form of V is proposed which utilizes knowledge of the errors. Monte Carlo variance estimates from generalized least squares (GLS) methods agree closely with the average variance estimates from GLS when the proposed V is used. Use of an estimated V, derived after the initial estimation procedure, is shown to provide adequate information on the variance of the estimates.

Selection for feed conversion on efficiency and growth in mice.

Selection for feed conversion substantially influenced growth and gross feed efficiency of mice. Realized heritabilities and genic correlation for increased gain on fixed feed intake (FF) and decreased feed intake on a constant gain (FG) were estimated to be .56, .73 and -.93, respectively. The genic correlations between FF and 56-day weight and between FG and 56-day weight were estimated to be .67 and -.95, respectively. The relative efficiency in changing FF or FG by selecting directly for 56-day weight was found to be .7 in either case. When efficiency was defined as the incorporation of biomass independent of maintenance, no difference was found between selection treatments. Differences in mature weight and feed intake approached significance with selected lines having higher means than controls. The absence of a correlated response in the ability to use energy for growth indicates that selection for feed to gain ratio changes maintenance requirements but not requirements for growth.