THE EFFECT OF ARTIFICIALLY EXTENDED PHOTOPERIOD DURING LACTATION ON MATERNAL PERFORMANCE OF THE SOW

A 20-stall farrowing facility was partitioned into two separate rooms of 10 stalls each so that photoperiod could be controlled. In addition, temperature and air movement were equalized in the two rooms. The two light regimens utilized were 8 h light: 16 h dark, and 16 h light:8 h dark. A total of 26 sows in two replicates were used. Females were moved into the facility on d 103 -+2 of pregnancy, litters were equalized at birth and weaning was at 28 d of age. Traits evaluated included litter size at birth and weaning, 21-d pig and litter weights, milk yield on d 15, survival rate and number of days from weaning to estrus for the sow. The number of pigs born alive was similar across treatments. However, after equalization of litter size, differences in the number weaned/ litter were significant (P\u3c.05) as sows exposed to 16 h of light weaned approximately one pig more per litter. The survival rate within each litter from birth (after equalization) to 21 d of age was greater (P\u3c.05) for sows exposed to 16 h light (91.2%) than for those from sows exposed to 8 h light (81.5%). Milk yield at d 15 was measured for 21 of the sows. The sows exposed to 16 h light produced significantly more milk (P\u3c.05) than sows exposed to 8 h light. The time from weaning to first estrus was similar for each treatment group

THE EFFECT OF ARTIFICIALLY EXTENDED PHOTOPERIOD DURING LACTATION ON MATERNAL PERFORMANCE OF THE SOW

A 20-stall farrowing facility was partitioned into two separate rooms of 10 stalls each so that photoperiod could be controlled. In addition, temperature and air movement were equalized in the two rooms. The two light regimens utilized were 8 h light: 16 h dark, and 16 h light:8 h dark. A total of 26 sows in two replicates were used. Females were moved into the facility on d 103 -+2 of pregnancy, litters were equalized at birth and weaning was at 28 d of age. Traits evaluated included litter size at birth and weaning, 21-d pig and litter weights, milk yield on d 15, survival rate and number of days from weaning to estrus for the sow. The number of pigs born alive was similar across treatments. However, after equalization of litter size, differences in the number weaned/ litter were significant (P\u3c.05) as sows exposed to 16 h of light weaned approximately one pig more per litter. The survival rate within each litter from birth (after equalization) to 21 d of age was greater (P\u3c.05) for sows exposed to 16 h light (91.2%) than for those from sows exposed to 8 h light (81.5%). Milk yield at d 15 was measured for 21 of the sows. The sows exposed to 16 h light produced significantly more milk (P\u3c.05) than sows exposed to 8 h light. The time from weaning to first estrus was similar for each treatment group

Perspectives for artificial insemination and genomics to improve global swine populations

Civilizations throughout the world continue to depend on pig meat as an important food source. Approximately 40% of the red meat consumed annually worldwide (94 million metric tons) is pig meat. Pig numbers (940 million) and consumption have increased consistent with the increasing world population (FAO 2002). In the past 50 years, research guided genetic selection and nutrition programs have had a major impact on improving carcass composition and efficiency of production in swine. The use of artificial insemination (AI) in Europe has also had a major impact on pig improvement in the past 35 years and more recently in the USA. Several scientific advances in gamete physiology and/or manipulation have been successfully utilized while others are just beginning to be applied at the production level. Semen extenders that permit the use of fresh semen for more than 5 days post-collection are largely responsible for the success of AI in pigs worldwide. Transfer of the best genetics has been enabled by use of AI with fresh semen, and to some extent, by use of AI with frozen semen over the past 25 years. Sexed semen, now a reality, has the potential for increasing the rate of genetic progress in AI programs when used in conjunction with newly developed low sperm number insemination technology. Embryo cryopreservation provides opportunities for international transport of maternal germplasm worldwide; non-surgical transfer of viable embryos in practice is nearing reality. While production of transgenic animals has been successful, the low level of efficiency in producing these animals and lack of information on multigene interactions limit the use of the technology in applied production systems. Technologies based on research in functional genomics, proteomics and cloning have significant potential, but considerable research effort will be required before they can be utilized for AI in pig production. In the past 15 years, there has been a coordinated worldwide scientific effort to develop the genetic linkage map of the pig with the goal of identifying pigs with genetic alleles that result in improved growth rate, carcass quality, and reproductive performance. Molecular genetic tests have been developed to select pigs with improved traits such as removal of the porcine stress (RYR1) syndrome, and selection for specific estrogen receptor (ESR) alleles. Less progress has been made in developing routine tests related to diseases. Major research in genomics is being pursued to improve the efficiency of selection for healthier pigs with disease resistance properties. The sequencing of the genome of the pig to identify new genes and unique regulatory elements holds great promise to provide new information that can be used in pig production. AI, in vitro embryo production and embryo transfer will be the preferred means of implementing these new technologies to enhance efficiency of pig production in the future

THE EFFECT OF ARTIFICIALLY EXTENDED PHOTOPERIOD DURING LACTATION ON MATERNAL PERFORMANCE OF THE SOW

A 20-stall farrowing facility was partitioned into two separate rooms of 10 stalls each so that photoperiod could be controlled. In addition, temperature and air movement were equalized in the two rooms. The two light regimens utilized were 8 h light: 16 h dark, and 16 h light:8 h dark. A total of 26 sows in two replicates were used. Females were moved into the facility on d 103 -+2 of pregnancy, litters were equalized at birth and weaning was at 28 d of age. Traits evaluated included litter size at birth and weaning, 21-d pig and litter weights, milk yield on d 15, survival rate and number of days from weaning to estrus for the sow. The number of pigs born alive was similar across treatments. However, after equalization of litter size, differences in the number weaned/ litter were significant (P\u3c.05) as sows exposed to 16 h of light weaned approximately one pig more per litter. The survival rate within each litter from birth (after equalization) to 21 d of age was greater (P\u3c.05) for sows exposed to 16 h light (91.2%) than for those from sows exposed to 8 h light (81.5%). Milk yield at d 15 was measured for 21 of the sows. The sows exposed to 16 h light produced significantly more milk (P\u3c.05) than sows exposed to 8 h light. The time from weaning to first estrus was similar for each treatment group