Roger R. Hacker

Pigs expressing salivary phytase produce low-phosphorus manure

To address the problem of manure-based environmental pollution in the pork industry, we have developed the phytase transgenic pig. The saliva of these pigs contains the enzyme phytase, which allows the pigs to digest the phosphorus in phytate, the most abundant source of phosphorus in the pig diet. Without this enzyme, phytate phosphorus passes undigested into manure to become the single most important manure pollutant of pork production. We show here that salivary phytase provides essentially complete digestion of dietary phytate phosphorus, relieves the requirement for inorganic phosphate supplements, and reduces fecal phosphorus output by up to 75%. These pigs offer a unique biological approach to the management of phosphorus nutrition and environmental pollution in the pork industry.

Melatonin concentrations in serum and tissues of porcine gastrointestinal tract and their relationship to the intake and passage of food

Abstract: Melatonin concentrations were determined in serum and 10 segments of the gastrointestinal tract (GIT) of 48 pigs (100 kg weight). The animals were fasted for 30 hr and then sacrificed 0, 1,2, 5, 10, and 20 hr after refeeding. Peak amount of gastric digesta (2,428 g) and ileum digesta (850 g) were observed 1 hr and 5 hr, after refeeding, respectively. Conversely, colon content reached a minimal weight (726 g) at 2 hr after refeeding. Serum levels of melatonin increased from 3.4 pg/ml to 15.5 pg/ ml (peak 5 hr after refeeding). Melatonin levels in GIT tissues before refeeding varied from 23.8 pg/g (stomach‐fundus) to 62.1 pg/g (rectum). Increasingly higher levels of melatonin were detected in the distal segments of the GIT. Higher melatonin levels after refeeding were observed in most GIT tissues except the rectum. In most tissues, peak melatonin values were detected 5 hr after refeeding. A significant change in weight of digesta across time (P<0.05) was detected in the stomach, ileum, and cecum. Similar changes in melatonin levels across time were found in most tissues except the esophagus, stomach (cardia and pylorus), and rectum. Adjacent GIT tissues exhibited similar (P<0.05) melatonin levels. The GIT melatonin levels correlated best with the variation of digesta weight in the ileum. In addition, the increase of serum melatonin levels correlated best with the increase of GIT melatonin levels in the distal part of the GIT. Our results suggest that melatonin produced in the ileum, cecum, and colon may contribute significantly to the short‐term increase of serum melatonin levels observed after refeeding.

Melatonin concentrations in the luminal fluid, mucosa, and muscularis of the bovine and porcine gastrointestinal tract

Abstract: Melatonin concentrations were measured in serum, luminal fluid, and tissues of the mucosa and muscularis of the entire bovine and porcine gastrointestinal tract (GIT). In both species, GIT levels profoundly exceeded serum levels. In pigs, melatonin was lowest in the luminal fluid and highest in the mucosa. No difference was found in various layers of bovine GIT. Compared to pigs, cows had higher melatonin levels in the stomach and ileum, but lower in the cecum and colon. There was no difference in melatonin levels between anterior and posterior segments of bovine GIT, whereas pigs exhibited several fold higher concentration of melatonin in the posterior segment (cecum and colon). Conversely, melatonin values in the anterior segment were significantly higher in cows, but in the posterior segments porcine values were higher. In cows, concentrations in the mucosa correlated with levels in the muscularis. Melatonin levels in the mucosa and muscularis were higher in the rumen and reticulum than in the omasum and abomasum. The species‐specific levels and a distinct distribution of melatonin in the layers of the digestive tube indicates that this indole may be involved in the modulation of gastrointestinal function of monogastric as well as polygastric ungulates, albeit in a different capacity.

Circadian variation of portal, arterial and venous blood levels of melatonin in pigs and its relationship to food intake and sleep

Circadian levels of melatonin were determined in the hepatic portal vein, cranial vena cava, and the lower aorta of ten juvenile pigs. Blood was sampled every hour for a total of 24 hr via temporary cannulas introduced into blood vessels under anesthesia. No peak levels of melatonin were found in the mid‐scotophase, but hepatic portal concentrations peaked at 06.00 hr. Overall levels of melatonin were highest in the hepatic portal vein (range 35–65 pg/mL), followed by an artery (range 30–55 pg/mL) and the vena cava (range 25–35 pg/mL). Levels of melatonin exhibit strong variation between individual pigs, but generally the average levels from all three sources follow each others time course. However, on occasion, melatonin levels in the hepatic portal vein varied independently from the levels in the vena cava. Large portal peaks were usually preceded by a feeding period and were associated with a subsequent period of sleep. The data indicate that: 1) there is no clear circadian rhythm of melatonin in the peripheral blood of pigs, 2) relatively little melatonin is metabolized during the first liver passage, 3) food intake may elevate melatonin levels in the hepatic portal vein, and 4) increased levels of melatonin originated in the gastrointestinal tract may induce sleep.

Chain elongation-desaturation of linoleic acid during the development of the pig. Implications for the supply of polyenoic fatty acids to the developing brain

Rates of chain elongation-desaturation of C18:2 omega 6 were compared for liver and brain microsomes in fetal, neonatal and postnatal piglets. Rates of chain elongation-desaturation of C18:2 omega 6 were greatest in liver and increased during perinatal development on a per organ basis. These results suggest that fetal liver and brain has the capability to chain elongate and desaturate essential fatty acids to longer chain homologues. For brain rates of synthesis of chain elongation-desaturation products was greatest during the newborn period whereas this metabolic function was greatest in liver in the postnatal stages of life examined.

Pork farm odour modelling using multiple-component multiple-factor analysis and neural networks

The number of non-farming rural residents surrounding pork farm operations has increased greatly in many pork-producing nations. These non-farming rural residents consider pork farm odour emissions to be a serious health threat. This has led to significant lobbying to limit the expansion and development of pork operations, and consequently reduced economic growth in the pork industry. This has led pork producers to search for effective methods to mitigate the odourous emissions, and researchers to seek methods to adequately model the odour. Extensive research has been performed on the use of single-component analysis to model the odour. Several researchers have used multiple-component analysis to extend the effectiveness of previous models. Since odour generation factors, like temperature, also contribute to the odour, the next logical approach to modelling pork farm odour is multiple-component multiple-factor analysis. It is proposed that the multiple-component neural network model be extended to make use of multiple-component multiple-factor analysis. First, a neural network model and a linear multiple regression model are developed and compared using multiple-component analysis to demonstrate the better modelling technique for pork farm odour. The neural network model of the pork farm odour yielded more accurate and precise odour intensity predictions than the linear multiple regression models, indicating that neural networks are the better modelling technique for this application. Subsequently, a multiple-component multiple-factor neural network model was developed and compared with the multiple-component neural network. The multiple-component multiple-factor neural network model generated performance gains, indicating that this approach is relevant to modelling pork farm odour. It is hypothesized that the extension of the multiple-component multiple-factor analysis to include additional significant odour components and odour generation factors in the neural network model will further improve model performance.

Genetic Opportunities tyo Enhance Sustainability of Pork Production in Developing Countries: A Model for Food Animals

Currently there is a shortage of food and potable water in many developing countries. Superimposed upon this critical situation, because of the increasing urban wealth in these countries, there is a strong trend of increased consumption of meat, and pork in particular. The consequence of this trend will be increased agricultural pollution, resulting not only from greater use of chemical fertilizer, but also from manure spread on land as fertilizer that may enter freshwater and marine ecosystems causing extensive eutrophication and decreased water quality. The application of transgenic technologies to improve the digestive efficiency and survival of food animals, and simultaneously decreasing their environmental impact is seen as an opportunity to enhance sustainability of animal agriculture without continued capital inputs. Transgenes expressed in pigs that have potential include, for example, genes coding for phytase, lactalbumin and lactoferrin. At the University of Guelph, Escherichia coli phytase has been expressed in the salivary glands of the pig. Selected lines of these pigs utilize plant phytate phosphorus efficiently as a source of phosphorus and excrete faecal material with more than a 60 percent reduction in phosphorus content. Because of their capacity to utilize plant phytate phosphorus and to produce less polluting manure they have a valuable trait that will contribute to enhanced sustainability of pork production in developing countries, where there is less access to either high quality phosphate supplement or phytase enzyme to include in the diet. Issues that require continued consideration as a prelude to the introduction of transgenic animals into developing countries include food and environmental safety, and consumer acceptance of meat products from genetically modified animals.

Synthesis of chain elongated−desaturated fatty acids from palmitic acid by liver and brain microsomes during the development of the pig

Rates of chain elongation-desaturation of C16:0 were compared for liver and brain microsomes in fetal, neonatal and postnatal piglets. Rates of chain elongation of C16:0 were greatest in liver in the postnatal period. For all developmental periods examined, the amount of chain elongated fatty acid of C20 or greater chain length exceeded the amount of C18 precursors synthesized from C16:0. These observations suggest that chain elongation of fatty acids occurs during the latter part of gestation at rates equivalent to that observed in the early postnatal period.

Analysing Contributions of Components and Factors to Pork Odour Using Structural Learning with Forgetting Method

A novel neural network based approach to analysing contributions of odour components and factors to the perception of pork farm odour is proposed. A multi-component multi-factor odour analysis model is developed and learnt by an algorithm called structural learning with forgetting. Through the learning, unnecessary connections fade away and a skeletal network emerges. By analysing the resulting skeletal networks significant odour components and factors can be identified, and thus a more thorough understanding of odour model can be obtained. The proposed approach is tested with a pork farm odour database. The results demonstrate the effectiveness of the proposed approach.