The health, well-being and future opportunities of young carers: a population approach.

Objectives: There is a lack of evidence on the health-related impacts of being a young carer. This article takes a population approach to young carer research specifically to investigate the prevalence of young carers and explore differences in their health, well-being and future expectations.

Study Design: This is a cross-sectional regression analysis.

Mixed tenure communities as a policy instrument for educational outcomes in a deprived urban context?

This article considers mixed community strategies, enacted through planning and regeneration policies, as a policy approach to the improvement of educational outcomes in schools. Analysis is undertaken of educational outcomes across secondary schools in Glasgow. The level of owner occupation in the catchment is positively associated with both examination results at S4 and positive destinations post-school, particularly at the more deprived end of the school spectrum.

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).

Characterization of a line of pigs previously selected for increased litter size for RBP4 and follistatin.

The objective of this study was to determine if selection response for increased litter size in pigs could be partially attributed to three type 1 marker loci coding for genes known to affect litter size: oestrogen receptor (ESR), retinol-binding protein 4 (RBP4) and follistatin (FS). In the high litter size line (LS), pigs from the largest litters, based on number of pigs born alive (NBA), were retained to parent the next generation. A randomly selected control line (LC) was maintained.

National Pork Producers Council Maternal Line National Genetic Evaluation Program: a comparison of sow longevity and trait associations with sow longevity.

Data from the National Pork Producers Council Maternal Line National Genetic Evaluation Program were used to compare longevity of sows from 6 commercial genetic lines and to estimate the phenotypic associations of sow longevity with gilt backfat thickness, ADG, age at first farrowing, litter size at first farrowing, litter weight at first farrowing, average feed intake during lactation, and average backfat loss during lactation. The lines evaluated were American Diamond Genetics, Danbred North America, Dekalb-Monsanto DK44, Dekalb-Monsanto GPK347, Newsham Hybrids, and National Swine Registry. The data set contained information from 3,251 gilts, of which 17% had censored longevity records (sows lived longer than 6 parities).

National Pork Producers Council Maternal Line Genetic Evaluation: a comparison of growth and carcass traits in terminal progeny.

The objective of this study was to compare growth and carcass traits of 1,252 progeny of six commercially available dam lines included in the National Pork Producers Council Maternal Line Evaluation Project. Lines compared included one maternal line supplied by each of American Diamond Swine Genetics (ADSG), Danbred NA (DB), two lines supplied by Monsanto Choice Genetics (DK and GPK347), Newsham Hybrids (NH), and Landrace x Large White females supplied by the National Swine Registry (NSR). All females were mated to DB, Duroc-Hampshire terminal sires.

Evaluation of procedures to predict fat-free lean in swine carcasses.

The objectives were to develop equations for predicting fat-free lean in swine carcasses and to estimate the prediction bias that was due to genetic group, sex, and dietary lysine level. Barrows and gilts (n = 1,024) from four projects conducted by the National Pork Board were evaluated by six procedures, and their carcass fat-free lean was determined. Pigs of 16 genetic groups were fed within weight groups one of four dietary regimens that differed by 0.

Effect of divergent selection for testosterone production on testicular morphology and daily sperm production in boars.

The objective of this study was to characterize correlated responses in testicular morphology and daily sperm production to divergent selection for testosterone production. Duroc boars from high and low lines (HTL and LTL, respectively) divergently selected over 10 generations for testosterone production in response to a GnRH challenge followed by random selection were used. Testicular tissues were sampled from all available males of generation 20 (HTL, n = 46; and LTL, n = 13).

The National Pork Producers Council Maternal Line National Genetic Evaluation Program: a comparison of six maternal genetic lines for female productivity measures over four parities.

Litter (n = 8,424) and female performance records were collected in two breed-to-wean production units in order to evaluate genetic line differences for sow longevity and maternal performance over four parities. Lines evaluated were American Diamond Genetics, Danbred North America, Dekalb-Monsanto DK44, Dekalb-Monsanto GPK347, Newsham Hybrids, and National Swine Registry. Females within a line were derived from a minimum of 65 sires, 197 dams (three dams per sire), and a maximum of three daughters per dam, except in the GPK347, which were produced using semen from 12 Nebraska Index boars mated with Dekalb-Monsanto Line 34 females.

Design and standards for genetic evaluation of swine seedstock populations.

The purpose of this article is to describe a program for evaluation of seedstock populations in the swine industry. Differences among seedstock populations for economically important traits must be identified in order for pork producers to efficiently use available genetic resources. National genetic evaluation programs have the potential to identify the important differences among populations and to increase the rate of genetic improvement in a population.

Results from nine generations of selection for increased litter size in swine.

Direct selection for increased litter size was done for nine generations. The select line consisted of approximately 15 sires and 60 dams per generation, and selection was based on estimated breeding values for number of live pigs. A control line of approximately 10 sires and 30 dams was maintained with stabilizing selection.

Genetic and nutritional effects on swine excreta.

The objective of this study was to investigate genetic and nutritional effects on swine excreta. Two studies were used. Study I was a 3 x 2 x 2 factorial design with three genetic groups, two diets, and two sexes.

Evaluation of crossbred calf and cow types for the coastal plain of North Carolina.

Data in this experiment consisted of 418 lactation records, and weaning and birth weight records from 600 crossbred calves. The traits evaluated included birth weight, weaning weight, weaning weight per cow exposed, weaning weight per weight of cow, weaning weight per weight of cow exposed, and predicted milk yield. Angus, Brangus, and Gelbvieh sires were mated to purebred Hereford cows.

Realized heritability estimates in boars divergently selected for testosterone levels(1,) (2).

Data were collected from 1982 through 1992 from 100 sires and 891 Duroc boars. Testosterone production was measured from peripheral blood samples before (PRE) and after (POST) GnRH challenge. Additionally, data were collected on testes volume at 168 d (TVOL), days to 104 kg (DAYS104), number born alive (NBA) and backfat adjusted to 104 kg body weight (FAT).

Integrated systems analysis of sow replacement rates in a hierarchical swine breeding structure.

Sow replacement rates in a three-tiered breeding structure were investigated for a 10-yr planning horizon using a stochastic life-cycle swine production model. Market hogs were produced in a three-breed static crossing program and marketed on a liveweight basis. Growth and reproductive traits of individual pigs were simulated using genetic, environmental, and economic parameters.

Genetic and economic analyses of sow replacement rates in the commercial tier of a hierarchical swine breeding structure.

Commercial-level sow replacement rates were investigated for a 10-yr planning horizon using a stochastic life-cycle swine production model. A three-tiered breeding structure was modeled for the production of market hogs in a three-breed static crossing scheme. Growth and reproductive traits of individual pigs were simulated using genetic, environmental, and economic parameters.

Evaluation of mating systems involving five breeds for integrated beef production systems: IV. Accounting for variability and genetic trends.

Computer models were used to simulate integrated cow-calf-feedlot production systems. Angus (A), Charolais (C), Hereford (H), Limousin (L), and Simmental (S) purebreds and two- and three-breed rotational crossbreds were included. Models were deterministic and based on data reported primarily from the 1970s.

Effects of pregnant mare's serum gonadotropin on reproduction in four genotypes of gilts(1).

Effects of PMSG and genotype on various measures of reproductive efficiency were investigated. Prenatal data were obtained at 40 d of gestation from 96 gilts representing four genotypes. Data on Duroc (D), Yorkshire (Y), Synthetic (Large White × Landrace) (SYN), and Crossbred Duroc × Yorkshire (XB) gilts were collected from January, 1990 through May, 1991.

Prediction of performance of progeny from test station boars.

Data were obtained from 1,954 Duroc and 2,252 Yorkshire purebred and crossbred progeny sired by 34 Duroc and 32 Yorkshire boars, respectively. Boars were purchased from the North Carolina Swine Evaluation Station during August 1983 to December 1988. Boars were selected to represent high and low indexes at the test station.

Genetic and economic analyses of female replacement rates in the dam-daughter pathway of a hierarchical swine breeding structure.

A stochastic life-cycle swine production model was used to study the effect of female replacement rates in the dam-daughter pathway for a tiered breeding structure on genetic change and returns to the breeder. Genetic, environmental, and economic parameters were used to simulate characteristics of individual pigs in a system producing F1 female replacements. Evaluated were maximum culling ages for nucleus and multiplier tier sows.

A bioeconomic simulation model for a hierarchical swine breeding structure.

A stochastic computer model was developed to simulate individual pigs in a hierarchical breeding system. The bioeconomic model was designed as a tool to facilitate the evaluation of selection, culling, and management strategies for a three-tiered breeding structure. Events such as mating, farrowing, and selection occurred weekly.

Evaluation of mating systems involving five breeds for integrated beef production systems: III. Integrated system.

Angus (A), Charolais (C), Hereford (H), Limousin (L), and Simmental (S) breeds were included in deterministic computer models simulating integrated cow-calf-feedlot production systems. Three mating systems were used: pure-breeding and two-and three-breed rotational crossbreeding. Breed information was taken from the literature.

Evaluation of mating systems involving five breeds for integrated beef production systems: II. Feedlot segment.

Computer models were used to simulate the feedlot segment of an integrated beef production system. Five breeds, Angus (A), Charolais (C), Hereford (H), Limousin (L), and Simmental (S), in three mating systems, pure-breeding and two- and three-breed rotational crossbreeding, were evaluated for feedlot and carcass performance. Breed data were taken from the literature.

Evaluation of mating systems involving five breeds for integrated beef production systems: I. Cow-calf segment.

Deterministic computer models were used to simulate the cow-calf segment of an integrated production system. Angus, Charolais, Hereford, Limousin, and Simmental breeds were included in three mating systems: pure-breeding (PB) or two- (2R) or three-breed (3R) rotational crossbreeding. Breed data were taken from the literature.

Effect of selection for litter size and body weight on hormone-induced ovulation rate in mice.

Genetic differences in natural vs hormone-induced ovulation rates were compared in immature female mice from five lines that had undergone long-term single-trait and antagonistic index selection for litter size and(or) 6-wk BW. Lines used were control (K); high litter size (L+); high BW (W+); low litter size and high BW (L-W+); and high litter size and low BW (L+W-). Natural ovulation rate at a mean age of 34.