Maximizing Growth Rate – Weaning to Market

Posted in: Prairie Swine Centre by admin on January 1, 2003 | No Comments

Throughput is important for maximized production. Faster growth rates do not hinder the quality of the pork produced. The relationship between growth rate, feed intake, and feed conversion contributes to the overall growth rate. Pigs gain muscle mass with increased protein in the diet as long as sufficient energy is available. It has been estimated that only about one-third of the protein consumed in the diet will be retained in the body as protein. Minerals, protein, and energy are all needed for growth. Excess protein will be used for energy, and excess energy will be deposited as fat. Genetics have allowed for different options when purchasing breeding stock. Current genetic improvements have resulted in an increase in the lean growth rate of up to 3% per year. As the lean content of the pig increases, feed efficiency improves. In order to support this increased growth, the supply of nutrients must also increase, through either increased feed intake or the use of more nutrient dense diets. Environmentally, pigs need to be in their thermal comfort zone to maximize feed intake without hindering growth rate. Heat emission from basic pig metabolism should be taken into account so that pigs do not get too hot in warm temperatures. The environment should successfully balance the heat loss with the heat production of the pigs. Newly weaned pigs should be in a room with a slightly higher temperature to make up for pigs that are not eating and losing heat. Typically, lower average daily gains and higher feed intake occurs among pigs in a cold environment. As a thumb rule, one can estimate that for every degree C below the thermal comfort zone, growth rate will decline by 10 to 22 g/d. While crowding is known to reduce growth rate and feed intake, increasing the density of the diet to achieve equivalent daily nutrient intake is not successful in returning the performance of crowded pigs to that achieved by non-crowded pigs. A healthy animal is important because the immune system requires energy to operate. Diet composition must be adequate (not too dense yet not too thin). Particle size is important for maximizing feed intake and efficiency, and research is still going on to determine the optimal particle size.

Transmission of PRRSV by non-porcine vectors: Recent research reports

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PRRS is generally passed into a herd via other pigs and semen. Researchers are working to analyze other routes of infection. It was found that needles transmit PRRS from PRRS positive pigs to PRRS negative pigs. Contaminated coveralls, boots and hands of people can transmit PRRS to non-infected pigs following the direct contact with infected pigs. Therefore it is good practice to change clothing and clean up after contact with PRRS positive pigs. Results have shown that with “real” conditions (meaning not an experimental set of conditions), PRRS may be transmitted over short distances with infected animal air space, but transmission of PRRS through the air between farms seems to be an infrequent event.

Houseflies and mosquitoes believe it or not serve as a mechanical method of PRRS transmission. The PRRS virus can survive in the fly for 12 hours and the mosquito for 6 hours following feeding on an infected pig, and as little as 1 fly is capable of transmission.

Behaviour and adrenal activity of first parturition and multiparous cows under a competitive situation.

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First parturition cows have to cope with several changes in their social and physical environment that can compromise their welfare and health. In addition to being separated from their calves, they have to compete for eating and lying places with unknown and more experienced cows once they are introduced into the milking herd. The present study was aimed at to compare the social and maintenance behaviour, and plasma cortisol levels after an adrenocorticotropic (ACTH) hormone challenge test as a mean of assessing the level of stress, of first parturition cows with those of adult cows. Cows were observed during 178 h in a cubicle building where social and maintenance behaviour was recorded. An adrenal function test was carried out after the observation period to determine cortisol levels in plasma before and after ACTH injection. First parturition cows spent more time walking and lying out of the cubicle during a 24-h period and during the night than adult cows. Cortisol levels at 60 and 90 min after injection of ACTH were lower in adult cows than in first parturition individuals. In heifers, the proportion of time feeding during the day was negatively correlated with cortisol levels at 60 and 90 min after ACTH administration, and in multiparous cows the proportion of time lying out of the cubicles in a 24-h cycle and lying out during the night were positively correlated to cortisol levels at 60 minute after ACTH administration. This information is useful to understand more about chronic stress in first lactation cows when introduced to a new herd and to make recommendations of management procedures to reduce welfare problems in these individuals.

Social effects on dustbathing behaviour in laying hens: using video images to investigate effect of rank.

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Dustbathing behaviour of hens was studied due to the assumption that the behaviour is socially facilitated, and social rank of hens was also investigated due to its importance in other aspects of hen social behaviour. After nine days of litter deprivation, both high and low ranked birds were tested by situating them in front of a video monitor displaying middle ranked birds, in a cage with sand on the floor. The test hens were allowed a one-hour habituation period in the test cage before the two-hour test phase began. Three different test videos of the middle ranking birds were used: a dustbathing hen, a standing hen, and an empty cage. Each test bird was allowed to see all three videos. Differences were found in the number of birds dustbathing, the number of dustbathing bouts, and the latency to dustbathe. Fewer dustbathing bouts and fewer initiations of dustbathing were observed among high-ranking birds compared with low-ranking birds when the video showed a standing bird. High-ranking birds began to dustbathe sooner if they were shown a video of another bird dustbathing compared with a video of a bird standing. In both high-ranking and low-ranking birds, effects on duration and intensity of dustbathing were not seen. The authors suggested two interpretations of the results: either the high-ranking birds were socially facilitated to initiate dustbathing by the video image of a dustbathing hen, or the high-ranking birds were inhibited in starting to dustbathe by the image of a standing bird. The authors then raised the question as to whether social facilitation is as clear a phenomenon as suggested by earlier workers, who only worked with feeding and drinking behaviours in hens.

Heritability of feather pecking and open-field response of laying hens at two different ages

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Feather pecking impairs animal welfare and results in higher feeding costs and increased mortality rates in laying hens. The objective of the current study was to estimate heritabilities (h2) of feather pecking and open-field response of laying hens at two different ages. An F2 cross, originating from a high and a low feather pecking line of laying hens, was used for the experiment. Each of the 630 birds of the F2 cross was subjected to an open-field test (individual, 10 min) at 5 and 29 wk of age and to a social feather pecking test (groups of five birds on wood shaving, 30 min) at 6 and 30 wk of age. Both tests were performed in a square open field and the behaviours of the birds were recorded directly from a monitor. Heritabilities of feather pecking and open-field behaviours were calculated. In the open-field test at 5 wk of age, high h2 were found for most traits, ranging from 0.20 for the frequency of flying to 0.49 for number of steps. In the social test at 6 wk, gentle feather pecking (0.12) and ground pecking (0.13) were found to be heritable. When both tests were repeated at 29 and 30 wk of age, h2 estimates were lower for the open-field test, ranging from 0.10 for duration of sitting to 0.20 for latency to first step. In the social test, however, higher h2 estimates of 0.15 for gentle feather pecking and 0.30 for ground pecking were found compared with 6 wk of age. In conclusion, gentle feather pecking and open-field behaviours may be used in selection against feather pecking.

Physiology and behaviour of the hen during induced molt.

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The easiest and most effective way to induce molt is through feed deprivation, and is therefore used by the commercial egg industry. However, there are concerns about the bird’s welfare under these conditions. The response to feed deprivation goes through three phases: 1) for the first few days, physiological and behavioural adjustments cause a reduction in protein catabolism and energy expenditure. Plasma corticosterone increases temporarily, which promotes gluconeogenesis and helps maintain glucose levels at the beginning of the fasting period. Hens become more alert, active and aggressive during the first two days of the molt; 2) During the second phase, energy is gained through the breakdown of lipids and proteins and the hens tend to rest more. This phase can continue for many months; 3) During the third phase, there is an acceleration of protein catabolism. Birds will stop eating and remain inactive during this period. Alternatives to current methods of induced molting are being investigated; for example, different methods of nutrient restriction that avoid long-term feed withdrawal, and the use of dietary additives.

Quantitative Selection for Piglet Survival as A Safe Way to Reduce the Cost of Weaners

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Improving piglet survival has three reasons, including general success in selection for increased litter size; larger litters increase the necessity of fostering, and concern for animal welfare. Losses in litter size occur in the uterus, farrowing, and pre-weaning. The survivability depends on the piglet’s genes, the maternal genes, and the milking sows genes (if fostered). Simultaneous selection for litter size and birth weight will increase birth weight dramatically, but will not increase survival nor increase litter size. Eight years of selection for litter size and piglet survival can increase litter size and survivability. Almost all economically important traits can be improved genetically. Even for a trait with a very low heritability (such as piglet survival) genetic progress can still be made. Some work being done is on survival and birth weight, survival and fatness, survival and feed intake, and survival and mothering ability.

Science, values, and common ground

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The goal of this paper is to explore the idea that animal scientists strive to improve the areas in animal production that opponents of animal production criticize. The four main areas that animal scientist strive to improve include: product quality, quality of life for food producers, fair treatment of human resources, and humane treatment of animals. It is also argued that there are differences between profit-motivated improvements and those motivated by ethical values. Some positive moral changes are revolutionary, most, however, result from the promotion of positive incremental changes, and being aware of the effects on deeds and attitudes. Positive change can result by becoming more aware of the objectives of scientific research. More critics of animal production should become aware that the welfare of animals is considered very important, and it is the objective of on-going research.

The Impact of Feeder Adjustment and Group Size/ Density on Weanling Pig Performance

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Crowding and/or reduced floor space allowance negatively affects nursery performance and exacerbates social vices such as tail biting, side nudging and ear chewing. Feeder adjustment impacts feed intake and can alter feeder capacity. Since some of the detrimental effects of crowding are due to decreased feed intake, adequate floor space and proper feeder adjustment may act in a synergistic fashion to improve pig performance. Seven hundred and sixteen pigs weaned at an average of 18.2 days of age were assigned to: 1) 24 pigs per pen, 2.5 ft2 per pig; 2) 20 pigs per pen, 3.0 ft2 per pig [approximates commercial conditions]; and 3) 16 pigs per pen, 3.75 ft2 per pig [approximates the Canadian Code of Practice] for a 42 day trial. Eight days later feeders were adjusted to provide gap openings of 9.2, 11.8, 17.9, 24.8 and 31.5 mm (see Figures 1 to 3). Only a small bead of feed was available with an opening of 9.2 mm while the entire trough was covered with an opening of 31.5 mm. Feeding behaviour was videotaped on days 3 to 6 and on days 39 to 42. On day 42, each pig was scored for incidence and severity of tail biting, side nudging and ear chewing. Providing more floor space resulted in increased body weight at 10 weeks of age. Performance was maximized when the feeder gap allowed for 40% of the trough to be covered with feed. Moreover, proper adjustment of the feeder reduced the time spent eating and thus increased feeder capacity.

The use of ensiled cassava leaves in diets for growing pigs. 2. The influence of type of palm oil and cassava leaf maturity on digestibility and N balance for growing pigs

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