A mathematical model for designing and sizing sow farms

Posted in: Environment by admin on January 1, 2004 | No Comments

Crowding effects on performance on fully and partially slatted floors

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Crowding affects the productivity of grow/finish pigs and it is generally believed that floor types differ in required space. This study was designed to determine if there is a significant interaction between the two factors. Crowding resulted in a reduction in ADG, but the type of flooring did not make a difference.

Variation: Costs and Consequences

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All-in-all-out (AIAO) systems are becoming popular in the industry. This is leading to the realization of the costs of slower growing pigs. Focus is now shifting towards total herd growth average and range in that growth. Statistically, variation can be measured by standard deviation (SD) and coefficient of variation (CV), both of which make use of the “bell curve”. The bell curve shows how many individuals are clustered around the average and how far they stray from the average (“deviate”). A narrow bell is desirable. Mean (average), median (middle observation in a range), mode (most frequent observation), minimum and maximum observations, SD, and CV are all useful in measuring variability. Measuring variation on-farm is difficult to do and the proper amount of pigs must be weighed to obtain acceptable results. The industry has developed management techniques to deal with variability such as cross fostering. Variation can affect production via sort losses, barn utilization, and effective phase feeding. Barn space is effected because faster growing pigs will go to market quicker and slower growing pigs will take several weeks longer. This will offset the flow of production. The most obvious cost of variation is in the carcass grading. In 2002, producers lost about $6.9 million based on Mitchell’s grading grid due to variability! Causes of this variation can be narrowed down to genetic and environmental. The goal of producers should be to minimize the influence of the environment on variability so that genetics is the lone contributor to variation. This description of variation can also be called “intrinsic” (factors based on the actual pig) or “extrinsic” (based on external factors such as the environment). Based on social behaviour, if average performance is good and variation low, it can be assumed that conditions are good because of little aggression. When performance drops it can be assumed that there is competition for resources such as food and water. This results in restriction of feed to some pigs, which will likely increase the variability. When variation in a facility is relatively low, management is the best key to handling it. If variation is high then it should be looked at to reduce variability. Reasonable CV targets are 20% weaning weights, 12 to 15% nursery exit weights and 8 to 12% for weight at first pull. If the CV is above target, look at reducing variability. If it is on target, work on managing the variability.

Impact of speed of growth and slaughter weight of pigs on performances, carcass and meat quality, and organoleptic properties of meat

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In Québec, pigs are slaughtered at an average weight of 107kg, but the market tends to seek heavier pigs. Two proofs were conducted to evaluate the impact of speed of growth and slaughter weight of commercial pigs (107, 115 and 125kg). It has been found that increasing slaughter weight reduced feed conversion, daily gain and the soluble collagen content but increased back fat and muscle thickness as well as carcass yield and loin eye area. Pigs born from fathers with GPI contributing to faster growth did grow faster and eat more each day, but their feed conversion and other zootechnical performances were not significantly affected. It also been found that slow-growing pigs had larger proportions of leg (primal and commercial cuts), primal shoulder (Boston) butt and commercial loin and a firmness of meat slightly higher. Speed of growth had no impact on number or size of fibers. As well, slaughter weight did not influence the number of muscle fibers, but pigs slaughtered at 107kg had shorter fibers. The meat of the pigs slaughtered at 107kg contained less protein. Faster growing pigs showed a larger belly, which had a lower “iodine” index, and acquired more fat and less muscle. As far as pigs slaughtered at 125kg are concerned, they exhibited a larger shoulder butt proportion, a higher-scored loin colour and a slightly higher firmness of meat. Our model showed that slaughter weight affected farm profitability, depending on various factors. Overall, neither increased slaughter weight nor faster growth had any major negative impact on meat quality.

Lying behaviour and adrenocortical response as indicators of the thermal tolerance of pigs of different weights.

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Optimal temperature ranges of fattening pigs at different weights were assessed by examining the behavioural and adrenocortical responses of pigs to a range of ambient temperatures. Cortisol concentration was analyzed by taking saliva samples from the pigs. Behaviours measured included lying behaviour. Depending on ambient temperature, pigs chose different areas for resting. When temperature increased, pigs would lie in the dung area away from penmates more often. Heavier pigs lied without contacting their penmates more often than their lighter counterparts. Lying without penmate contact occurred 5 to 7 °C lower than lying in the dung area. As temperature decreased, huddling behaviour increased. As pig weight increased, huddling occurred more at lower temperatures. For pigs over 85 kg body weight, there was a significant increase in cortisol levels when ambient temperature increased. The results of the present study indicated that, for pigs weighing 25 to 35 kg and housed on partially slatted floors, temperature range within the thermal tolerance of pigs was 19 to 21 °C. At 50 to 70 kg body weight, the range was 10 to 17 °C. For pigs over a body weight of 85 kg, temperature range within their thermal tolerance was 5 to 17 °C.

The effect of rearing regime on the development of the mammary gland and claw abnormalities in high genetic merit Holstein-Friesian dairy herd replacements.

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The effect of rearing regime on mammary gland development and claw abnormalities was assessed using Holstein-Friesian heifers. Treatments included 1) heifers reared to calve at 540 kg and offered grass-silage based diets during the winter and grass-based diets during the summer; 2) heifers reared to calve at 620 kg and offered grass-silage based diets during the winter and grass-based diets during the summer. They also received additional supplements; 3) heifers reared to calve at 620 kg and were offered a straw/concentrate diet during the winter and a grass-based diet during the summer; 4) heifers reared to calve at 620 kg and fed a straw/concentrate diet in both the winter and summer and were housed. By increasing the plane of nutrition, the weight of dissected udder fat increased, but there was no effect on the weight or chemical composition of dissected udder parenchyma. Fat deposition in the udder was reduced and the proportion of parenchyma in the udder was increased by offering straw- compared with silage-based diets. There were no effects on weight of fat when heifers were housed during the first summer and offered straw-based diets compared with those heifers turned out to grass, although there was a tendency towards a reduction in the proportion of parenchyma in the udder. Values for heel height, lateral claw length and heel erosion scores were lower for heifers reared on a low plane of nutrition. A higher plane of nutrition increased live weight/sole area, although it was only significantly higher for treatment 3 compared with treatment 1 heifers. Housing heifers the first summer increased the incidence of feet lesions in the white line and solear area relative to turning heifers out to grass that first summer.

Effect of duration of cold stress on plasma adrenal and thyroid hormone levels and immune responses in chicken lines divergently selected for antibody responses.

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There is increasing evidence that stress affects various immune processes. Some of these changes are due to hormonal changes involving corticosterone (CORT), triiodothyronine (T3), and thyroxine (T4). Effects of stress depend on the nature of specific stressors (e.g., thermal extremes, diet, pollutants), stress-modifiers (e.g., genetic make-up, duration and severity of the stressors). This study examined the effects of a specific stress (cold stress) with stress-modifiers (duration of stress and genotype of the bird) on immune responses and plasma adrenal and thyroid hormone levels in 3 layer-type chicken lines. Two lines were divergently selected for high (H line) or low (L line) antibody responses to SRBC, and the third line was a randombred control (C). Growing chicks of the 3 lines were feed-restricted at 80% of ad libitum consumption, and subjected to cold stress (CS) at 10oC continuously for 7, 5, 3, 1 or 0 d before immunization with keyhole limpet hemocyanin (KLH). Specific antibody titers to KLH, and in vitro lymphocyte proliferation (LP) upon mitogen stimulation were measured. In addition, adrenal and thyroid hormone levels were measured in the plasma samples collected at the end of CS. No significant effect of duration of CS on specific antibody titers was found in the 3 lines. A significant enhancing effect of CS was found on LP. A significant dose-dependent suppressive effect of CS was found on plasma CORT levels. The authors concluded that CS does not affect specific antibody responses, but may have a modulating effect on cellular immunity and plasma CORT levels, depending on the duration of stress. This is the first study that reveals an absence of significant differences in adrenal and thyroid hormone levels in the described selection lines.

Complexity of behavioural sequences and their relation to stress conditions in chickens: a non-invasive technique to evaluate welfare.

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This study examined the use of behavioural complexity as a potential to assess the stressfulness of an animal’s environment. Chickens were videotaped for 0.5 hr periods and the changes in behaviour analysed to yield a complexity value. This technique was then used to determine the effects on behavioural complexity when birds were exposed to different potential stressors. Differences were found in the behavioural complexity of locomotor and resting behaviours when birds were exposed to food restriction, social crowding through the addition of more birds, and when sand was provided. The direction of these changes was not consistent for all stressors, however, the authors conclude that behavioural complexity is a non-invasive means to assess different housing conditions.

Are cows that consistently enter the same side of a two-sided milking parlour more fearful of novel situations or more competitive?

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This study attempted to find a relationship between the consistency that a cow enters a one of two sides of a milking parlour with her behaviour in a novel environment and her ability to attain fed in a competitive situation. Two groups of twelve cows were chosen from a group of 70. Cows that demonstrated a preference for entering only one side of the parlour were classified as high consistency (HC) cows and entered in the preferred way, on average, 91% of the time. Cows that did not show a strong preference for either entry entered one side 60% of the time and were classified as low consistency cows (LC). For fifteen-minute period after milking, a cow was housed in a new empty pen and her behaviour was observed. Immediately after that set of observations, another cow was introduced to the pen and feed was provided in the bucket. The behaviour of the cow was recorded for 15 minutes or until the two cows stopped feeding or interacting with one another. When HC cows were introduced to the empty pen, they stood motionless longer than LC cows. However, HC and LC cows showed similar amounts of exploratory behaviours (time spent sniffing the pen, number of steps taken, number of vocalizations) when moved into the pen. The authors interpreted the difference in activity as indicating that HC cows were more fearful of the new environment. When a new cow and feed was introduced to the pen the HC cows were began to eat the food sooner and maintained control of the bucket longer than LC cows. HC cows were involved in more aggressive interactions and tended to push the other cow more than LC cows. During the feed competition test, the HC cows stood inactive longer than the LC cows. All cows likely develop some sort of a routine. There is, however, a difference in the social strategies between cows with strong and weak preferences. Those cows that are able to demonstrate a preference may be more capable of successfully executing their social strategy.

Organic livestock production in Europe: Aims, rules and trends with special emphasis on animal health and welfare

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In Europe, organic farming has increased during the last decade. However, the market share is still relatively low. The needs of animals are better met in organic farming systems than in conventional systems. The goal of organic farming is to ensure high standards of product quality, animal health and welfare. As a result, there are high demands on management qualifications. However, there are no guarantees that the high standards will be maintained. The development of quality assurance programs has been suggested in order to ensure that standards are maintained. The criteria for sustainability can only be realized if the standards for animal health and welfare and product quality and environmental security are maintained.