Ad libitum Feeding of Gilt Developer Diets Differing in Standard Ileal Digestive Lysine Concentrations Affected Growth and Feed Efficiency but did not Affect Age at Puberty in Replacement Gilts

The effect of ad libitum feeding diets with three lysine concentrations to developing gilts housed in groups from 100 to 220 days of age on growth, body composition, feed efficiency and age at puberty was evaluated. Gilts were randomly allotted to three corn-soybean diets formulated to provide three standardized ileal digestible (SID) lysine concentrations. Gilts received grower diets formulated to provide 0.68% (low), 0.79% (medium) or 0.90% (high) SID lysine from 100 days of age until approximately 90 kg BW. Then, gilts were fed finisher diets containing 0.52% (low), 0.60% (medium) or 0.68% (high) SID lysine until they were moved to the breeding barn at approximately 220 days of ageData on BW, bakfat thickness, loin area, feed and lysine intake and age at puberty was collected at different intervals during the study. Gilts fed the low lysine diet had lower average daily gain, body weight, backfat thickness and loin depth compared with gilts fed the high lysine diet. Overall, 34% of gilts displayed standing estrus before 220 days of age. The number of gilts that reached puberty was not different among dietary treatments; however, gilts fed the high and medium lysine diet reached puberty 10 days and 6 days before gilts fed the low lysine diet, respectively. Results from the present study suggest that growth rate can be successfully altered when feeding gilts ad libitum diets differing in SID lysine concentration without negatively affecting puberty attainment

Controls of Litter Size—Do Conclusions Drawn from Institutional Research Herds Always Have Relevance to Commercial Swine Production?

Increasing litter size in pigs has been an ongoing concern of many producers because it has the greatest impact on profitability of the swine enterprise. To study the biology of conceptus growth and survival, many models have been used by researchers. It was determined that a major component in limiting litter size results from the impacts of limitations in uterine space (i.e. uterine capacity). Placental efficiency, which is the ratio of a fetus’s weight compared with that of its placenta, has been shown to impact litter size, and is heritable. Selection for breeding animals having a high placental efficiency at term, has been shown to increase litter size. Furthermore, although piglet weight was only slightly decreased in offspring of boars and gilts selected for increased placental efficiency, placental size was profoundly reduced. This reduction in placental size was coupled with an increase in vascularity, thus nutrient and oxygen uptake by the conceptus could be accomplished over a decreased surface area of attachment to the uterine wall. Reproductive data obtained to date have been gathered largely from university swine herds that may have little relevance to commercially used US pig breeds. In contrast to the constant evaluations of physiological changes associated with increased litter size at universities, swine seed stock producers have selected for many generations simply on increased litter size and have not bothered to evaluate the resulting physiological changes associated with increased fecundity. Therefore, it was the objective of this study to investigate the reproductive characteristics of a commercially relevant swine herd in Iowa (PIC Camborough Line) at selected gestational ages. Multiparous sows (ranging from 1 to 14 parities) were slaughtered on days 25, 36, and 44 of gestation, time periods corresponding to intervals which are before, during, and after the time when uterine capacity becomes limiting. At the laboratory, the uterine horns were measured and ovulation rate was determined. Conceptuses were removed and fetal and placental weights were determined. Uterine horn length and ovulation rate did not differ between the three gestational groups. Conceptus number decreased from 15.8 ± 0.6 on day 25 to 12.9 ± 0.5 and 12.1 ± 0.4 on day 36 and day 44 (litter size in this population averages ~11.5 liveborn piglets/litter). Conceptus survival to day 25 was 60.2 ± 0.1%, which then decreased to 50.1 ± 0.1% on day 36 and 46.3 ± 0.1% on day 44. There was a positive correlation between conceptus number and ovulation rate on day 25 but by day 36 this association was lost. Conceptus number was not associated with uterine length on day 25, but by day 36 there was a positive association that remained through day 44. On all three gestation days there was a negative association between conceptus number and placental weight, but no association between conceptus number and fetal weight was observed, indicating that larger litters are comprised of conceptuses having small placentae, but the same sized fetuses. These data indicate that, compared with commonly reported values for university herds (16-18 ovulations), ovulation rate in these mixed parity production animals is extremely high, whereas conceptus survival as estimated from the number of conceptuses divided by the number of ovulations was very low. Additionally, although conceptus number was related to the ovulation rate on day 25, by day 36 the limitations of uterine size began to reduce conceptus number irrespective of ovulation rate. These data suggest that ovulation rate is not a limiting factor in litter size in this line of commercially relevant pigs. In contrast, the higher than expected ovulation rate observed in these pigs resulted in significant embryo losses and early uterine crowding. The consequences of this early conceptus crowding may have detrimental impacts on prenatal and postnatal growth rate and survival

Optimal Dietary Energy and Protein for Gilt Development: Age at Puberty, Ovulation Rate, and Reproductive Tract Traits

The effect of feeding different lysine and metabolizable energy (ME) levels to 1221 crossbred Large White × Landrace developing gilts housed in groups from 100 d of age until slaughter (approximately 260 d of age) on age at puberty and reproductive tract measurements were evaluated. Gilts were randomly allotted to six corn-soybean diets formulated to provide two standardized ileal digestible lysine levels [100% (high, HL) and 85% (low, LL)] and threemetabolizable energy levels [ME, 90% (low, LME), 100% (medium, MME), 110% (high, HME). Average age at puberty was 193 d of age. There were no effects of the dietary treatments on age at puberty or any of the reproductive tract measurements. Despite significant differences in the lysine:energy ratio in the diets, the expected differences in reproductive traits were not observed. Other factors such as body weight (BW) and days of estrous cycle had a greater effect on the traits recorded than feed provided

Job applicants’ attitudes towards cognitive ability and personality testing

Orientation: Growing research has shown that not only test validity considerations but also the test-taking attitudes of job applicants are important in the choice of selection instruments as these can contribute to test performance and the perceived fairness of the selection process. Research purpose: The main purpose of this study was to determine the test-taking attitudes of a diverse group of job applicants towards personality and cognitive ability tests administered conjointly online as part of employee selection in a financial services company in South Africa. Motivation for the study: If users understand how job applicants view specific test types, they will know which assessments are perceived more negatively and how this situation can potentially be rectified. Research design, approach and method: A non-experimental and cross-sectional survey design was used. An adapted version of the Test Attitude Survey was used to determine job applicants’ attitudes towards tests administered online as part of an employee selection process. The sample consisted of a group of job applicants (N = 160) who were diverse in terms of ethnicity and age and the educational level applicable for sales and supervisory positions. Main findings: On average, the job applicants responded equally positively to the cognitive ability and personality tests. The African job applicants had a statistically significantly more positive attitude towards the tests than the other groups, and candidates applying for the sales position viewed the cognitive ability tests significantly less positively than the personality test. Practical and managerial implications: The choice of selection tests used in combination as well as the testing conditions that are applicable should be considered carefully as they are the factors that can potentially influence the test-taking motivation and general test-taking attitudes of job applicants. Contribution: This study consolidated the research findings on the determinants of attitudinal responses to cognitive ability and personality testing and produced valuable empirical findings on job applicants’ attitudes towards both test types when administered conjointl

Genes, gametes and gestation outcomes - essential links in a successful breeding management program

Foxcroft, George. (2011). Genes, gametes and gestation outcomes - essential links in a successful breeding management program. Retrieved from the University Digital Conservancy, https://hdl.handle.net/11299/139842

Six weeks abroad in Ireland, England and Belgium. With an appendix.

Mode of access: Internet

Controls of Litter Size—Do Conclusions Drawn from Institutional Research Herds Always Have Relevance to Commercial Swine Production?

Increasing litter size in pigs has been an ongoing concern of many producers because it has the greatest impact on profitability of the swine enterprise. To study the biology of conceptus growth and survival, many models have been used by researchers. It was determined that a major component in limiting litter size results from the impacts of limitations in uterine space (i.e. uterine capacity). Placental efficiency, which is the ratio of a fetus’s weight compared with that of its placenta, has been shown to impact litter size, and is heritable. Selection for breeding animals having a high placental efficiency at term, has been shown to increase litter size. Furthermore, although piglet weight was only slightly decreased in offspring of boars and gilts selected for increased placental efficiency, placental size was profoundly reduced. This reduction in placental size was coupled with an increase in vascularity, thus nutrient and oxygen uptake by the conceptus could be accomplished over a decreased surface area of attachment to the uterine wall. Reproductive data obtained to date have been gathered largely from university swine herds that may have little relevance to commercially used US pig breeds. In contrast to the constant evaluations of physiological changes associated with increased litter size at universities, swine seed stock producers have selected for many generations simply on increased litter size and have not bothered to evaluate the resulting physiological changes associated with increased fecundity. Therefore, it was the objective of this study to investigate the reproductive characteristics of a commercially relevant swine herd in Iowa (PIC Camborough Line) at selected gestational ages. Multiparous sows (ranging from 1 to 14 parities) were slaughtered on days 25, 36, and 44 of gestation, time periods corresponding to intervals which are before, during, and after the time when uterine capacity becomes limiting. At the laboratory, the uterine horns were measured and ovulation rate was determined. Conceptuses were removed and fetal and placental weights were determined. Uterine horn length and ovulation rate did not differ between the three gestational groups. Conceptus number decreased from 15.8 ± 0.6 on day 25 to 12.9 ± 0.5 and 12.1 ± 0.4 on day 36 and day 44 (litter size in this population averages ~11.5 liveborn piglets/litter). Conceptus survival to day 25 was 60.2 ± 0.1%, which then decreased to 50.1 ± 0.1% on day 36 and 46.3 ± 0.1% on day 44. There was a positive correlation between conceptus number and ovulation rate on day 25 but by day 36 this association was lost. Conceptus number was not associated with uterine length on day 25, but by day 36 there was a positive association that remained through day 44. On all three gestation days there was a negative association between conceptus number and placental weight, but no association between conceptus number and fetal weight was observed, indicating that larger litters are comprised of conceptuses having small placentae, but the same sized fetuses. These data indicate that, compared with commonly reported values for university herds (16-18 ovulations), ovulation rate in these mixed parity production animals is extremely high, whereas conceptus survival as estimated from the number of conceptuses divided by the number of ovulations was very low. Additionally, although conceptus number was related to the ovulation rate on day 25, by day 36 the limitations of uterine size began to reduce conceptus number irrespective of ovulation rate. These data suggest that ovulation rate is not a limiting factor in litter size in this line of commercially relevant pigs. In contrast, the higher than expected ovulation rate observed in these pigs resulted in significant embryo losses and early uterine crowding. The consequences of this early conceptus crowding may have detrimental impacts on prenatal and postnatal growth rate and survival.</p