Advanced treatment of swine wastewater by electrodialysis with a tubular ion exchange membrane

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Why do we measure digestibility?

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The following article discusses research conducted at the Prairie Swine Centre and on a commercial farm evaluating the impact of feeding diets with increasing digestible energy content. Although we can estimate the energy content of the diets using published values for each ingredient we have based our results on the DE content which we measured. This involves determining the caloric content of the feed in a lab and measuring feed intake in the barn. We also must determine caloric output, – collecting faeces and determining the caloric content of what is excreted. Although this may sound like fun, it is actually quite time-consuming and expensive, – so why don’t we just use the published values?
The following graphs show data from several digestibility experiments. The top graph is from grow-finish experiments. If the measured values equaled the formulated, then the data would follow the line. The difference between the formulated and the measured ranged from 17 kcal to 175 kcal. This can be a significant difference, however, the difference appears random, and therefore, using the measured values would not bias our results in one direction. Conversely, as can be seen in the lower graph, when weanling pigs are used, not only are the measured different from the formulated, but the measured is always less, therefore, if we didn’t actually measure digestibility our estimated values would not only be variable, but would be consistently too high.
The variability in the diet DE content observed in both the grower and weanling pigs is due to the natural variability in the DE content of various grains (ie. see COS ). The bias observed with the weanling pigs is because published DE values are based on grower pigs. Because of anatomical and development differences, digestibility in the younger pigs is always lower.
As can be seen in the following article, a difference in DE content of only 100 kcal can significantly impact feed costs and net returns. Therefore our research will continue to be based on actual, rather than formulated DE values, and collecting and grinding faeces will be part of our day!

Feeding for the Optimum Carcass

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The overall objective of any feeding program is to maximize net income while producing a high quality pork product for the consumer. Both carcass quality (fat and lean content) and pork quality (colour, taste, texture) need to be considered as outcomes of our feeding programs, as they both reflect the needs of the marketplace. The primary dietary contributors to pork quality are energy and amino acids. Sufficient amino acids must be in place in the pig’s diet to support the growth of lean tissue; the biggest risk in amino acid nutrition is inadequate supply, as the penalty of oversupply is primarily expense. On the other hand, in the case of energy, both under and oversupply can adversely affect the final pork product. Insufficient energy in the diet will result in slow growth and a leaner carcass, while excess energy will result in a fatter carcass. The type of fat in the diet is important, as it will affect the type of fat deposited in the carcass. Other nutrients, such as vitamins C and E, show promise in improving carcass quality, as do additives such as chromium, conjugated fatty acids, magnesium aspartate and ractopamine. However, while the benefits of their use have been fairly well defined, the economics of these various feed additives depends on many factors, including the cost of the product itself. Since few are currently available in Canada, it is difficult to evaluate their potential economic return. Finally, the manner in which the feed is presented to pigs, such as fasting before shipping, or feeding on a restricted scale as compared to ad libitum, can also affect carcass and pork quality. Feed restriction is not commonly practiced in Canada, because it can reduce net income if applied to pigs for too long a period.

Nutritional Manipulation of Pork Quality: Current Opportunities

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Current market demands are for “normal” pork to meet domestic and export consumption and to meet specialized markets. Quality pork is the combined result of genetics, nutrition, production management, transportation, slaughter, processing and retailing. There are a number of promising nutrients that have been shown to positively affect pork quality. Feeding protein or amino acid deficient diets will increase marbling. The downside is that this will impair growth performance and increase carcass fatness. Chromium works like insulin (lets the body absorb sugar) and may play a role in increasing rates of lean deposition. Betaine helps out methionine, which is an essential amino acid. Aside from being used for protein synthesis, it is also essential for many bodily chemical reactions. Adding betaine to diets has shown some potential to increase carcass leanness and/or growth performance. Magnesium has the potential to reduce energy-producing rates triggered by stress hormones. Creatine can be synthesized from 3 amino acids and works as a quick energy source for muscles. Feeding creatine may have the potential to improve pork quality. Feeding vitamin E is reported to significantly reduce drip loss in several studies. It will be of great value when pork products are developed with high levels of omega-3 fatty acids. Conjugated linoleic acid (CLA) may help in the fight against diseases and even cancer. It could also reduce carcass fat, increase lean and possibly even improve feed efficiency.

Modeling the effects of stressors on the performance of populations of pigs.

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A simulation model predicting effects of social, physical, and nutritional environments on pig food intake and performance was extended to account for individual variation. The goal was to investigate the effects of between animal variation on the performance of a population of growing pigs. It has been previously suggested that pigs with a leaner, more modern genotype may be less able to cope when exposed to social stressors. Similarly, it has been suggested that a pig’s position within the social hierarchy may affect ability to cope with social stressors. In the model, it was assumed that larger, more dominant pigs would be better able to cope when exposed to social stressors. The model showed that increasing initial body weight variation and the number of stressors increased the variation in pig performance. In commercial operations, where population variation may affect the profitability of the enterprise, this model may be an important practical consideration. The way a stressor effects performance determines whether the mean population response and the average individual response will be the same. If all the pigs in a group were affected at the same intensity by the stressor, then predicted mean and average individual responses would be the same. If the intensity of the stressor affected each pig differently, then differences between the individual and mean population responses would be predicted. Variation in initial body weight and social stressors were better determinants of the variation in growth response than a variation in growth potential was when pigs were housed in conditions similar to those found in commercial environments. In conclusion, decreasing the variation in initial body weight and improving the ability of pigs to cope may be a better for improving pig performance than selecting for increased growth potential alone.

Further evaluation of nonfeed removal methods for molting programs

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Laying hens that have completed a 40 week laying period may be put through a molt (loss of feathers and cessation of lay) and then begin a second laying period. Many methods used to induce this temporary stoppage of lay involve dramatic if not complete feed withdrawal. This raises serious welfare concerns. Alternative methods of inducing a molt have been developed. In this study several nonfeed withdrawal methods were compared with conventional programs (10 day withdrawal). The nonfeed withdrawal methods involved changing the diets to 94% corn, 94% wheat midlings, 71% wheat midlings:23% corn, 47% wheat midlings:47% corn, 95% corn gluten, and 94% distillers dried grains. The feed withdrawal programs achieved complete cessation of lay within a few days. With the exception of the distillers dried grains, all of the nonfeed withdrawal treatments reduced egg production to less than 6% during the program. Once laying was re-induced by the provision of a high quality laying diet there were no differences among treatments on egg production or quality. The results indicate that several nonfeed withdrawal programs are effective in inducing a molt and that subsequent production is unaffected.

Emotional reactions to learning in cattle.

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It has been suggested that when an animal’s own actions result in a reward, the animal shows signs of excitement and pleasure. Therefore, the expectation of a reward might be just as exciting as the realization that they themselves have contributed to the delivery of the reward. Information about this phenomenon would provide more insight into animal self-awareness. The current study involved a yoked control experiment involving the acquisition of an operant task. The aim was to distinguish between the reactions of animals that had learned on their own versus those that just received a food reward. Heifers were studied in pairs, each pair had a control and experimental animal. Experimental heifers were conditioned for 14 days to open a gate by pressing a panel, which gave them access to a food reward. For control heifers the gate opened after a delay equal to their matched partner’s latency to open it. Improvements in learning by the experimental heifers resulted in higher heart rates and more vigorous movements towards the food reward than the control heifers. There is some indication that a cow’s own learning improvement may result in an emotional reaction.

Effect of chronic clenbuterol administration and exercise training on immune function in horses

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Effects of longitudinal exercise training and acute intense exercise (simulated race test) on immune function have not been reported in horses. This study investigated the interaction of 8 week of exercise training with or without 12 week of clenbuterol administration in horses. Twenty-three untrained standardbred mares were used and divided into four experimental groups. Horses given clenbuterol plus exercise and clenbuterol alone received 2.4 ìg/kg BW of clenbuterol twice daily on a schedule of 5 days on and 2 days off for 12 weeks. Mares given exercise alone were aerobically trained for 3 days/week, and the control group remained sedentary. Lymphocyte proliferative response was not affected by clenbuterol or exercise treatment. From the present experiment it was apparent that horses demonstrated responses to bouts of acute exercise as noted with other species, namely humans and rodents.

Excess cortisol interferes with a principal mechanism of resistance to dehydration in Bos indicus steers.

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This study investigated the effects of excess cortisol on physiological mechanisms that resist dehydration in Bos indicus steers during a 90-h period. Steers were assigned randomly to one of four groups: 1) no water/ no cortisol, 2) water/no cortisol, 3) no water/cortisol, and 4) water/cortisol. Animals in the cortisol group were given a 0.1 mg.kg BW-1.h-1 of hydrocortisone suspended in isotonic saline for the duration of the study. Total body water, osmality, hematocrit, urine out put, feed and water intake, and plasma concentrations of arginine vasopressin (AVP), angiotensis II (AII), electrolytes, total protein, and albumin were determined at 24-h intervals for 90h. The results of this study highlight the complexity of endocrine interactions associated with water balance. Excess cortisol has a suppressive effect on the rennin-angiotensin-aldosterone axis; however it does not affect the circulating concentration of arginine vasopressin. In the presence of water deprivation, cortisol may serve to protect and maintain water balance at times of stress.

Chronic increase of dietary L-tryptophan decreases gentle feather pecking behaviour.

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The neural transmitter serotonin (5-HT) and the serotinergic system are involved in several abnormal behaviour patterns in animals. In this study the authors examined the relationship between this system and the incidence of feather pecking in 7 week old chickens. 5-HT is derived from tryptophan and they increased serotonin levels by increasing dietary tryptophan. Chicks were fed either the control diet with 0.16% tryptophan, or the treatment diet with 2%. Two lines of laying birds were used. Tryptophan reduced the incidence of gentle feather pecking, but only a trend in the same direction was found for severe feather pecking. Physiological measures confirmed that the high levels of tryptophan increased blood levels of the amino acid and increased serotonin in the central nervous system. High tryptophan also resulted in an increase in cortisol levels in the blood, which has been reported as a physiological effect of the amino acid previously. High levels of dietary tryptophan was effective in reducing levels of feather pecking in young chicks.