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International audience; The objective of this study was to estimate the genetic parameters for thermoregulation traits and the relationships with performance of Large White lactating sows reared in a tropical humid climate. The thermoregulation traits were rectal temperature (RT), cutaneous temperature (CT) and respiratory rate (RR) during lactation measured in the afternoon (1200 h) and in the morning (0700 h). The production traits were sow’s average daily feed intake (ADFI), litter BW gain (LBWg) and sow’s proportion of BW change between farrowing and weaning (BWc). Complete data included 931 lactating performance on 329 Large White sows from the INRA experimental unit in Guadeloupe (French West Indies). Random regression models using linear spline functions were used for longitudinal data (RT, CT, RR and daily feed intake). Results showed that when ignoring values at the beginning and the end of lactation, the traits studied can be treated as the same trait throughout days of lactation, with fairly constant heritability and variance. However, largest heritabilities and genetic variances were estimated in mid-lactation. Heritability estimates on average performance during lactation were low to moderate for thermoregulation traits (0.35±0.09 for RT, 0.34±0.12 for CT and 0.39±0.13 for RR). Heritability estimates for production traits were 0.26±0.08 for ADFI, 0.20±0.07 for BWc and 0.31±0.09 for LBWg. Significant genetic correlations between thermoregulation traits and production traits were only obtained for ADFI and RR (0.35±0.12). From this study it can be concluded that thermoregulation traits are heritable, indicating that there are genetic differences in heat stress tolerance in lactating Large White sows.

We propose a novel modeling framework to study the effect of covariates of various types on the conditional distribution of the response. The methodology accommodates flexible model structure, allows for joint estimation of the quantiles at all levels, and involves a computationally efficient estimation algorithm. Extensive numerical investigation confirms good performance of the proposed method. The methodology is motivated by and applied to a lactating sow study, where the primary interest is to understand how the dynamic change of minute-by-minute temperature in the farrowing rooms within a day (functional covariate) is associated with low quantiles of feed intake of lactating sows, while accounting for other sow-specific information (vector covariate)., 30 pages, 4 figures, 3 tables

Este trabalho foi realizado com o objetivo de definir parâmetros térmicos adequados para o projeto de sistemas de resfriamento e aquecimento de pisos, visando ao conforto térmico das matrizes e leitões nas maternidades. Inicialmente, três placas pré-moldadas de argamassa armada foram construídas, utilizando-se métodos distintos, visando à circulação de água resfriada para as matrizes e água aquecida para os leitões. A placa designada P1 foi construída com vazios no formato de serpentinas, em seu interior sem a presença de tubos. Na placa P2, utilizou-se tubo corrugado de polietileno, em forma de serpentinas, embutido na argamassa armada. Na placa P3, adotou-se o mesmo método de construção da placa P1, variando-se apenas a área de circulação de água. Na placa P1 atingiu-se uma temperatura superficial de aproximadamente 1 oC superior à P2 para uma mesma temperatura da água de entrada nas placas. No entanto, optou-se pela utilização da placa P2 , em razão da maior facilidade de construção e maior inércia térmica.

Analysis of the Relationship Between Fatness of Late Pregnant and Lactating Sows and Selected Lipid Parameters of Blood, Colostrum and MilkThis study determined the relationships between backfat thickness in sows on day 104 (±2) of pregnancy, changes in fatness between high pregnancy and lactation (day 21), the body weight of late pregnant sows, the level of selected lipid parameters in blood serum, and basic components and fatty acid profile of colostrum and milk. Backfat measurements were taken using an ultrasound device at the P1, P2, P3 and P4 sites and loin eye height was measured at the P4M site. In late pregnant sows, fatness measured at P1, P2, P3 and P4 and the mean of measurements taken at P2 and P4 were correlated with HDL (+0.491**, +0.537**, +0.439*, +0.483** and 0.529**, respectively). Measurements taken at P4 and the mean of P2 and P4 were correlated with cholesterol (CHOL, +0.367* and +0.372*, respectively). Correlations were also found between the level of fatness of pregnant sows (P2, P3, P4, (P2 + P4)/2) and the level of HDL at the end of lactation (+0.534**, +0.440*, +0.412* and +0.487**, respectively). The body weight of late pregnant sows was significantly correlated with the energy and fat levels in colostrum (-0.467** and -0.429*, respectively). In addition, it was correlated with the proportion of fatty acids in the profile (C18:2 +0.417*, C18:3 +0.493*). Correlations were observed between P1 backfat thickness and the proportion of colostrum fatty acids (C18:1 +0.483*, CLA +0.475*), and between P2 backfat thickness and the C20:4 content of milk (-0.421*). A relationship between backfat thickness measured at farrowing and the levels of selected fatty acids in colostrum was found for P2 and C18:3 (+0.471*), P3 and C18:0 (-0.608**), C18:2 (+0.463*) and C18:3 (+0.517*), and P4M and C16:1 (-0.513*). The greater the difference in P1 backfat thickness between late pregnancy and weaning, the higher the content of fat (+0.549**), energy (+0.510*), C18:0 (+0.493*) and CLA (+0.488*), and the lower the content of C14:0 (-0.512*) and C16:0 (-0.457*) in milk. The strong correlations of fatness in late pregnant sows and of changes in fatness during late pregnancy and weaning with some blood, colostrum and milk parameters suggest that sows should be evaluated for fatness during their productive life.

The effect on sow milk of variable levels of cassava in lactating sow diets was analyzed in an attempt to explain the beneficial effects reported by producers of including cassava as a basal feed. Twenty crossbred lactating sows were randomly assigned to five dietary treatments. The treatments were: i) broken rice (BR) as the basal feed (BR100), ii) 50% of BR replaced with cassava chip meal (CCM) (CM50), iii) 75% of BR replaced with CCM (CM75), iv) CCM as the basal feed (CM100), and v) dried boiled cassava chips (CCB) as the basal feed (CB100). The hydrocyanide (HCN) content of CCB was reduced to be intermediate between HCN in the no cassava (BR100) and the 50% cassava (CB50) diets. Hydrocyanide was 0.54, 3.24, 4.41, 5.43 and 1.77 ppm in the BR100, CM50, CM75, CM100 and CB100 diets, respectively. Increasing cassava did not affect feed intake (p>0.05), but increased HCN intake (p), lactoperoxidase (LPO), and glutathione peroxidase (GPx) activity. At farrowing, sow milk composition was not affected by experimental diets (p>0.05), but milk increased as the intake of HCN increased in sows diets (p = 0.96. At mid-lactation (day 14), milk composition was not affected (p>0.05). The milk quality levels of were 9.4, 10.3, 10.5, 11.6 and 9.1 ppm for the BR100, CM50, CM75, CM100 and CB100 diets, respectively (p = 0.01). The LPO contents were 16.41, 42.13, 51.42, 53.94 and 22.81 unit/L, respectively (p = 0.03). There was no GPx activity found in sow milk. When BR was replaced with cassava meal, total microbes and coliforms were reduced 78% and 87%, respectively, by the influences of HCN. The reported beneficial effects of cassava chip meal as a basal feed in lactating sow diets is manifested by improved performance of suckling pigs. This is due to beneficial, non-toxic levels of HCN in the diets. Besides passing HCN to suckling pigs in the form of , sow milk may also benefit suckling pigs with the observed (day 14) increase in lactoperoxidase content and reduction in coliform bacteria.

Voluntary feed intake in sows after parturition may be related to the capacity of the sow to cope with the numerous changes occurring around farrowing. This experiment was undertaken to investigate whether the feed intake during lactation was related to the reactivity of the sow during gestation and plasma Trp and cortisol concentrations. On d 58 of pregnancy, 37 sows were individually placed in a novel environment, and their behavior was observed during a 5-min open-field test. This test allowed the selection of 12 reactive (R) and 8 nonreactive (NR) sows for the study. Sows were fed 3 kg of a standard gestation diet/d before farrowing and a standard lactation diet ad libitum thereafter. The behavioral reactivity of sows when a human touched their neck in the farrowing crate was evaluated on d 72 of gestation, and their behavior during farrowing was analyzed. Sows were catheterized on d 70 of gestation, and blood samples were taken after an overnight fast on d 37 before farrowing, daily during the week before and the week after parturition, and on d 14 and 21 of lactation for plasma Trp and cortisol determination. The NR sows were less reactive to human contact (P=0.02), had a shorter farrowing duration (P=0.02), and tended to have a shorter birth interval between piglets (P=0.09) than the R sows. Feed intake was greater for the NR sows than for the R sows during wk 1 of lactation (P=0.02), as well as during the whole lactation (P=0.03). Plasma cortisol concentration was maximal on the day after farrowing (P=0.01) and returned to basal concentration within 4 d postpartum. No relationship was observed between sow behavior and plasma concentration of cortisol. For both groups of sows, plasma concentrations of Trp between d 2 and 4 postpartum were less than during gestation (P

The objectives of this study were to de- termine the effects of shading wallows during the sum- mer months on lactating sow behavior, performance, and physiology. A total of 128 sows were used during warm weather (May to August 2001) to determine the effects of unshaded (control; n = 8) vs. shaded (SH; n = 8) wallows. Sows ranged over 6 parities and were fed a completely balanced sorghum-based diet. Behavioral data were collected by 15-min scan samples over a 24-h period/wk for a total of 16 wk. All sows were observed twice when litter age was 5 and 15 d, respectively. Res- piration rates (breaths/min) were collected on 50 sows (control, n = 25; SH, n = 25) over an 8-wk period when the maximum temperature exceeded 32°C. Ten milliliters of clotted blood and 20 mL of whole blood were obtained by jugular puncture from each sow on the day of weaning to determine total white blood cells, acute phase proteins, packed-cell volume, and chemot- axis and chemokinesis. Descriptive water temperature profiles were measured by using data loggers positioned at 3 levels per wallow: surface water, shallow mud, and deep mud. Behavioral, postural, location, performance, and physiological measurements did not differ (P > 0.05) among wallow treatments. Regardless of treat- ment, sows spent approximately 82% of their total time budget inside the farrowing hut and only approximately 7% of their total time budget in the wallow. A total of 428 piglets died, 219 in the control treatment and 209 in the SH treatment. The majority of piglets in both treatments died of crushing within the first 72 h after parturition, and most of the piglets had suckled. Shade kept the shallow water profile cooler during the hotter afternoon temperatures compared with the control wal- lows. In SH for both the shallow and deep mud profiles, temperatures were consistent throughout the day. In conclusion, sows spent a large percentage of their daily time budget inside the farrowing hut and spent only brief episodes in the wallow. Shading the wallow did not result in increased wallow use time or improvements in sow physiology and overall performance.

A total of thirty sows (Landrace×Yorkshire) were used to determine the effects of dietary coconut fat powder supplementation on performance, nutrients digestibility, blood and milk characteristics. A feeding trial was conducted for 21 days from parturition to weaning. Experimental diets were supplied for 1 week before the parturition day and throughout the experimental period. Dietary treatments included: 1) CON(basal diet), 2) CFP (basal diet added 0.5% coconut fat powder) and 3) CFH (basal diet added 0.5% coconut fat power containing husk). An average daily feed intake was significantly improved in CFP and CFH treatments compared with CON treatment (P

Increased genetic selection and capacity for milk production in dairy cows has been associated with a decline in fertility. Following parturition, nutritional requirements increase rapidly with milk production and the resulting negative energy balance (NEBAL) extends for 8–10 weeks of early lactation. NEBAL delays the timing of first ovulation through attenuation of LH pulse frequency and low levels of blood glucose, insulin and IGF-I that collectively limit oestrogen production by dominant follicles. NEBAL results in mobilization of adipose tissue and loss of body condition score (BCS), which is strongly associated with the length of the postpartum anovulatory period. Failure of ovulation of the first wave dominant follicle is associated with elevated nonesterified fatty acids and ketones in plasma and greater accumulation of triglycerides in the liver during the first 3 weeks of lactation. NEBAL is related to lower fertility in dairy cows both through inhibition of ovulation in early lactation and effects exerted later during the breeding period. Management strategies to minimize the inhibitory effects of NEBAL on first ovulation should begin during the prepartum transition period and include maintaining moderate BCS and energy intake through parturition. Modern sows have been improved genetically for higher productivity including ovulation rate, litter size and milk production. Peak milk yield is achieved within 10 days after farrowing with consequent massive mobilization of body fat and protein mass. Conservation of body protein mass (

We studied how “sow-controlled” housing (i.e. housing where sows can leave their piglets at will) affects the behaviour and performance of sows and litters when tested under near-commercial conditions and with two different levels of piglet diet quality. Sows and litters were housed in pens where sows had access to a piglet-free area (“sow-controlled”, n=28) or did not have such access (“confined”, n=26). Half of the litters in each treatment had access to a standard diet offered as creep feed from day 7, and the other half had a more complex diet that was richer in protein and fat. Piglets with access to the more complex diet consumed 50% more solid food before weaning than piglets provided the standard creep feed, and continued to eat more after weaning (days 29–49). The complex diet did not affect piglet body weight at weaning or at the end of the experiment, but did result in 52% greater weight gain during the first week after weaning. There were no other effects of diet or diet by housing interactions. Sows in the confined pens nursed their piglets 10% more often than did those in the sow-controlled pens and consumed 18% more food during lactation (i.e. until day 28). Before weaning, piglets in sow-controlled housing ate 65% more solid food than those in the confined pens, but the confined piglets weighed 11% more at weaning (day 28). With their greater intake of solid food before weaning, piglets in sow-controlled housing lost less weight on day 29 than did piglets from confined litters, but they still weighed less at the end of the experiment (14.5±0.4 kg versus 15.8±0.4 kg). Of the sows in the sow-controlled housing, those that spent the most time away nursed their piglets less often, consumed less food, and lost less weight over lactation; piglets of these sows consumed more creep feed before weaning, lost less weight on the day of weaning and gained more weight during the following week. Thus, both high-complexity creep feed and sow-controlled housing led to small improvements in piglet performance at weaning, as long as the mother spent considerable time away from the piglets. The sow-controlled housing may also provide advantages to the sows, especially in terms of reducing the demands of lactation.

Se evaluó el efecto de la adición de nopal (Opuntia ficus- indica) a la dieta de cerdas lactantes sobre la producción y calidad de la leche. 22 cerdas hibridas (Yorkshire x Landrace x Pietrain), próximas al parto fueron seleccionadas al azar, con las que se formaron dos grupos (G): G testigo (GT) (n=11) cerdas que recibieron alimento balanceado ad libitum y G experimental (GE) (n=11) cerdas que recibieron 1% d-1 de nopal cerda-1 (con respecto al peso corporal de la cerda antes del parto) más alimento balanceado ad libitum durante 21 días de lactación. Las variables evaluadas fueron: producción láctea en los días 6, 10 y 15 postparto, así como los porcentajes de: lactosa, proteína y grasa en leche en los días 3, 11 y 17 de lactación. La información recabada se analizó mediante la metodología de mediciones repetidas y las diferencias entre grupos se obtuvieron a través de medias de mínimos cuadrados. No se encontró efecto de grupo sobre la producción láctea (P = 0.4904). Sin embargo, el pico de producción láctea fue al 15vo día de lactación: 9.1 y 8.7 kg de leche para GE y GT, respectivamente. Los promedios (%) generales de los componentes físico-quimicos de la leche: lactosa (6.6±0.57), proteína (4.5±0.40) y grasa (7.9±1.6) no fueron afectados por el grupo (P>0.05). La adición de nopal a la dieta de cerdas lactantes no modifica la producción ni los componentes físico-químicos (proteína, lactosa y grasa) de la leche de las cerdas lo que asegura el desarrollo del lechón del nacimiento al destete (21 días de edad).

The aim of the study was to evaluate the consequences of a divergent selection for residual feed intake (RFI) during growth in a temperate environment (TEMP) on sow performance in a tropical environment (TROP). Sows came from a selection experiment conducted at INRA in which 2 lines were selected for larger (RFI(+)) or smaller (RFI(─)) feed intake than predicted from performance. In the first analysis, a subsample of data obtained in TROP conditions (49 lactations) was compared to those obtained in TEMP on their sibs mated with the same boars (54 lactations). In the second analysis, data obtained in the TROP environment (82 lactations) were analyzed for testing the effect of season (warm vs. hot) and line on sow performance. Except for the lactation length, the interaction between line and climatic environment was not significant for the others traits (P > 0.05). The ADFI expressed per kilogram of litter BW gain tended to be higher in the RFI(+) line bred in the TROP environment (P = 0.080), together with piglet BW at weaning, which tended to be lower (P = 0.080). The ADFI was lower in TROP than in TEMP (4.56 vs. 5.86 kg/d; P = 0.003), with negative consequence on litter BW gain and maternal BW loss. The RFI(-) sows tended to eat less feed than RFI(+) sows during lactation (4.55 vs. 5.86 kg/d; P = 0.099). Litter BW at weaning was higher in the RFI(─) line. The RFI(─) sows ate significantly less feed to produce 1 kg of litter than the RFI(+) sows and tended to lose a larger amount of BW during lactation than the RFI(+) sows (2.40 vs. 3.02 kg/kg and -0.66 vs. -0.39 kg/d, respectively, P < 0.10). Whatever the line, ADFI was reduced by about 21% in the hot season (P < 0.05). Litter BW gain was depressed (P < 0.05) in the hot season (1.72 vs. 2.08 kg/d in the warm season; P = 0.023). Lactation maternal BW loss tended to increase in the hot season (1.10 vs. 0.71 kg/d in the warm season; P = 0.016), but back fat loss remained constant (P = 0.295). In the TROP environment, the amount of feed required to produce 1 kg of litter was not influenced by the line in the warm season (2.53 kg/kg on average; P = 0.99), but it tended to be lower in the RFI(─) line when compared to the RFI(+) line in the hot season (2.06 vs. 3.45 kg/kg; P = 0.050). This higher apparent efficiency in RFI(─) sows was mainly related to greater maternal body reserve mobilization (i.e., BW and back fat losses). In conclusion, selection for low RFI during growth in a TEMP environment did not impair sow and litter performance in tropical conditions.

The short lactation period of the modern sow is critical for determining the success of piglet survival and growth. Increases in milk production during early lactation may result from increases in secretory cell numbers, enhancement of functional differentiation of cells, or both mechanisms. The porcine mammary gland undergoes substantial growth during lactation. Mammary tissue wet weight can increase by more than 50% and total mammary gland DNA by 100% during a 21-day lactation. Postpartum mammary growth parallels the increase in milk production observed during lactation. Mammary growth during lactation is affected by litter size, dietary intake, and gland location, as well as by a number of other factors. A primary factor influencing postpartum mammary growth is removal of milk from the gland. A suckled mammary gland, in combination with the piglet that suckles it, form an interdependent growing unit. Mammary glands which are underdeveloped at parturition can still grow rapidly in response to suckling. The sow’s mammary gland has tremendous potential for growth during early lactation. Approaches for enhancing mammary gland growth during early lactation offer substantial potential for enhancing milk yield and piglet growth.

There is little doubt that the nutrient requirements of the lactating sow require further investigation. Levels of productivity are increasing well beyond those employed in earlier empirical studies; consequently, the need for more precise factorial calculations becomes increasingly apparent. It must be recognized that factorial estimates of nutrient requirements are not yet sophisticated enough to describe optimum feeding programs, those strategies that define the method of feeding during gestation and during lactation, or phases within each, to maximize overall productivity or efficiency. For example, there is now considerable activity devoted to the feeding of gilts and sows to achieve a desired body composition, much as is done in broiler breeders. Finally, the relationship among productivity, nutrition and endocrine status is an emerging and exciting new development. Because hormone status plays such an obvious role in reproduction, new information in this area can only benefit the efficient management of the breeding herd.

The objective of this study was to develop a technique to cannulate the mammary venous system of the lactating sow in conjunction with the carotid artery. A total of 16 sows were subjected to surgery between d 3 and 6 of lactation. The dams were separated from their litter during the full surgical procedure and the post-surgical recovery period. The carotid artery was cannulated according to a previously described method. The mammary vein cannulation immediately followed the carotid artery cannulation. A small venous branch (approximately 4 mm in diameter) located on the lateral side of the thoracic region was used to obtain access to the mammary vein. It was isolated 4 to 5 cm above the plica lateralis, between the first and second anterior gland. The venous branch was exposed and a cannula inserted slowly for a distance of 16 cm or until the tip of the cannula would reach the most cranial point of the mammary vein. The cannula was allowed to follow the normal path of blood flow, running in a caudal to cranial direction. After recovery from surgery (1 to 2 h), the dams were returned to their respective litters and treated with antibiotics for a minimum of 6 d. All sows nursed and weaned normal litters. Cannulas were flushed with heparinized saline (20 U/mL) every 8 h and both arterial and venous blood samples (10 mL) were collected simultaneously at 0700, 1500, and 2300. Arterial and venous cannulas remained patent for a minimum of 15 d.(ABSTRACT TRUNCATED AT 250 WORDS)

Avaliou-se o efeito do resfriamento do piso da gaiola de maternidade no desempenho produtivo de porcas em lactação no período de verão. Utilizaram-se 42 porcas entre o 1º e o 5º partos, distribuídas em delineamento experimental de blocos ao acaso com 3 tratamentos e 14 repetições, considerando cada porca uma unidade experimental. Os tratamentos foram assim constituídos: piso sem resfriamento e consumo à vontade; piso com resfriamento e consumo de 5,5 kg/dia; piso com resfriamento e consumo à vontade. Os animais mantidos em gaiola com piso com resfriamento e que receberam ração à vontade apresentaram maior consumo de ração, de energia metabolizável e de lisina digestível. A mobilização de reservas corporais foi maior nas porcas mantidas sobre o piso com resfriamento com alimentação restrita, as quais apresentaram também maior intervalo desmame-estro. Os leitões das porcas mantidas sobre o piso com resfriamento tiveram maior peso ao desmame e ganho de peso diário. As porcas lactantes mantidas no piso com resfriamento apresentaram menor frequência respiratória, temperatura retal e temperaturas superficiais da nuca, do pernil e do peito. O resfriamento do piso da gaiola de maternidade favorece a dissipação de calor corporal, melhorando a condição térmica, a capacidade de consumo e o desempenho produtivo de porcas em lactação durante o verão. The effect of cooling the forrowing cage floor on production performance of lactation sows in the summer was evaluated. Forty-two sows from to the 1st to the 5th parturition were allotted to a completely randomized block experimental design with three treatments and 14 repetitions, considering each animal an experimental unit. The treatments were the following: floor not cooled and free intake; floor cooled and 5.5 kg/day of intake; floor cooled and free intake. The sows maintained in cage with cooled floor and fed ad libitum showed greater feed intake, metabolizable energy and digestible lysine. Mobilization of body reserves were greater in sows kept on the cooled floor and receiving restricted food, and they also presented longer interval between weaning and estrus. Piglets of sows kept on cooled floor showed greater weight at weaning and daily weight gain. Lactating sows kept on the cooled floor presented lower values for respiratory frequency, rectal temperature and superficial temperatures of nape, ham and breast. Cooling the farrowing cage floor favors the dissipation of body heat, improving thermal condition, the capacity of feed intake and the productive performance of lactating sows in the summer.

This paper describes investigation of introduction of teat disinfection in lactating sows in order to reduce piglet mortality due to alimentary infections. The investigation was carried out at pig-breeding farm and included 50 sows divided in 2 equal groups. Group 1 served as control and in group 2 teats of the sows were daily treated with commercial antiseptic. The diagnosis of piglet death due to alimentary infections was based on post-mortem analysis. Piglet death percentage due to alimentary infections was lower in experimental group compared to the control. The results demonstrated that teat disinfection in lactating sows may serve as efficient biosecurity measure with the aim of reduction and prevention of piglet death due to alimentary infections.

Forty-eight Large White gilts were divided at mating into three feeding groups, low (L), medium (M) and high (H), and were fed during pregnancy, respectively, 1.8 kg day −1 , 2.25 kg day −1 and 2.7 kg day −1 of a diet containing 17% protein. During lactation they received the same diet ad libitum. Feeding and standing behaviour was recorded during the whole lactation by using infra-red cells connected to a microcomputer. Feeding bouts shorter than 10 min were considered as within meal intervals. Average daily feed intake over lactation decreased from Group L to Group H. Number of meals per day (8.7 on average) was not significantly different among the three groups, but average meal duration and meal size decreased during the first 2 weeks of lactation when gestation feed allowance increased. It was concluded that the effect of feeding level during gestation on feed intake during lactation is mainly associated with shorter meal duration and smaller meal size without any influence on the number of meals per day. A strong diurnal pattern of feed intake was apparent and similar in the three groups. About 72% of the meals and 73% of feeding activity occurred during the day phase. The same diurnal pattern was found for standing behaviour that was often related to feeding, since 67% of standing activity was associated with feeding behaviour.

Improvement in the efficiency of milk synthesis in the sow can be accomplished only with a thorough understanding of the metabolic mechanisms relating nutrient intake to lactational performance. We have begun to describe these connections systematically and quantitatively through mathematical modelling. Our model is an integration of our present knowledge base with concepts of lactating sow metabolism. It is limited by serious inadequacy of present information, but it has guided us to ask key questions which can be investigated by animal experimentation. We are presently studying the metabolism of lipids in adipose tissue, and the impacts of lysine and amino acid intake on metabolic state and lactational performance, to elucidate aspects of the connection between nutrient intake and lactational performance. The pressing need for more information at several levels of biological organization is described. Collaboration among scientists across disciplines can increase the productivity and efficiency of both scientific and practical endeavours. It is imperative that publication of research results include thorough descriptions of animals, diets and environments to allow better interpretation and use of results.

Ambient temperatures above the evaporative critical temperature (ECT) of lactating sows lead to a reduction in food intake, milk yield, reproductive performance and growth rate of piglets. The fall in food intake of the lactating sow is closely associated with a rise in deep body temperature as is also observed in growing pigs. Evidence is presented indicating that the reduction in milk yield of sows exposed to high temperatures may be greater than would be expected from an equivalent decline in food intake for sows housed under thermoneutral conditions. It is suggested that the direct effect of high temperatures on milk yield may result from a redirection of blood flow to the skin and away from other tissues, including the mammary gland. Experimental observations showing that skin temperature is maintained while deep body temperature declines after initially rising rapidly in lactating sows exposed to 28°C for four days lends indirect support to this theory. Oxygen uptake of lactating sows was observed to decrease from 523 to 411 ml/min when ambient temperature was increased from 18 to 28°C. This decline of 20% in heat production was associated with a 25% decline in milk yield and a 40% reduction in food intake. The oxygen uptake of lactating sows was found to be similar to that of non-breeding animals with an equivalent food intake. Consequently, ECT for lactating and non-lactating animals was found to be similar. Performance of lactating sows exposed to high temperatures can be improved by reducing the animal's heat production through decreasing the fibre and increasing the fat content of the diet. However, increasing heat loss from the sow, particularly through increasing the area of wet skin, has a greater positive effect on animal performance than modifying the diet.

Quantitative and qualitative milk production is the basis for determining the nutritional requirements of lactating sow; indeed, the gross nutrient composition of sow’s milk is frequently used as a suitable starting point when formulating milk-replacer diets for piglets. Data about the sow’s milk can be found from the literature but, in authors knowledge, no data on milk composition of Nero Siciliano sow exist. This study reports the preliminary results concerning some physical and chemical characteristics of the milk of this autochthonous Sicilian pig race during the lactation.The research was carried out on 10 “Nero Siciliano” sows, 4 primiparous (age: 9-12 months) and 6 pluriparous (age: 2-5 years), stabled in single boxes and fed with a concentrate. From the 10th day after farrowing to the weaning (day 58th), every week, in the morning, the sows were injected with 5 IU oxytocin (i.m.) and hand-milked; all functional mammary glands were milked. Piglets were removed and isolated from the dams fo...

A mathematical model of lactating sow metabolism was evaluated using three types of tests. First, 16 experimental treatments from four experiments reported in the literature were simulated with the model, and the simulated values for change in BW and protein and fat content were compared to reported or calculated values. Second, the model's response to level of feed intake, level of milk production, BW and composition at farrowing, and dietary lysine concentration was compared to expected responses. Third, the model's sensitivity to changes in several of its kinetic parameters was measured. There was good agreement between simulated and measured values for BW and fat loss and reasonable agreement for body protein loss. All responses to changes in external conditions were in expected directions and biologically reasonable. The model seemed rather robust with respect to changes in the kinetic parameters considered, although important changes in simulated values were found in some cases. Overall, the model seems sound. It can be useful in evaluation of feeding programs and in understanding biological relationships.

Management of the lactating sow influences milk production and subsequent reproduction through changes in nutrient intake. The management goal during lactation is to maximize feed intake. Decreasing the effective environmental temperature, increasing the nutrient density of the lactation diet, maintaining fresh adequate supplies of feed and water, and preventing excess weight gain during the prior gestation period will increase nutrient intake during lactation. Effective environmental temperature of the lactating sow can be maintained in the thermoneutral zone by using drip cooling, increased ventilation rates and flooring materials with superior conductive properties. Sow parity, genetics, litter size, and disease level will also influence feed intake. Management practices must account for these factors and, thus, should be tailored to individual farm situations to ensure adequate nutrient intake and prevent aberrations in subsequent reproductive performance.

Equations were developed to describe milk production and composition in the lactating sow on the basis of maximum yield curves diminished by low nutrient availability and low body reserves. Milk output was given first priority on available nutrients, with high efficiency (0.72 and 0.82 for energy and protein, respectively), followed by support costs, which in turn, were dependent on level of production. Availability of nutrients for maternal tissue accretion was determined to be highly dependent on the ratio of energy to protein in the diet, and diminished markedly at higher levels of intake. Dietary energy availability ranged from 0.95 to 0.77 and protein availability between 0.8 and 0.57 at the extremes of intake examined. The ratio of dietary energy to protein also proved to be an important determinant of milk output and the composition of body tissue mobilisation. The resulting model predictions closely approximated the responses observed in practice and provided a valuable means of evaluating nutritional strategies for the reproducing sow.

In 2007, two new populations of feral swine were discovered in Nance and Valley counties, Nebraska, USA. Necropsies and serologic testing was done on two individuals from the Nance County herd. Results indicated that a lactating sow had positive antibodies for pseudorabies virus (PRV). Investigations conducted by Nebraska Game and Parks Commission Law Enforcement division confirmed that the infected individual was transported illegally to Nebraska, USA, from Texas, USA. All domestic swine herds located within an 8 km radius of the infected individual tested negative for antibodies to PRV. Our results provide a clear example of how diseases can spread because of anthropogenic activities and highlight the need for disease surveillance and monitoring in the import of invasive species.

In the U.S.A., housing for the lactating sow and her piglets can be divided into five main areas. Total confinement, defined as the farrowing crate, houses the highest number of sows at 83.4 4.0%. Remaining operations house fewer sows with open buildings that have outside access at 12.4 4.1%, open building with no outside access, 2.9 0.5%, lot with hut or no building, 0.6 0.2% and pasture with hut or no building the lowest at 0.7 0.3% (NAHMS, 2000). In the U.K., it is estimated that around 70% of sows farrow in crates, 27% farrow outdoors in farrowing arks and only 3% farrow in loose-housed indoor systems (BPEX, 2004). Farrowing crates have become widely accepted by the industry for numerous reasons: it has made sow management easier, it allows for a higher stocking density of sows/unit of land and it can help to reduce piglet mortality (Fraser and Broom, 1997). However, the farrowing crate has received criticism due to potential detrimental effects it may inflict on the welfare of the sow. The prevalence of decubital ulcers (Davies et al., 1996; Rountree et al., 1997), behaviours considered maladaptive (Cronin and Wiepkema, 1984; Rushen, 1984; Haskell andHutson, 1996), and a limitation on allowing the sow complete postural adjustments are a few considerations. The development of an alternative, economical farrowing system that retains the advantages of the conventional farrowing crate could be beneficial to the industry (Collins, 1987). Alternative outdoor swine operations for the gestating sow are increasing in popularity in some countries. In 1975, only 6% of the U.K.’s national herd was housed outdoors. This trend can be seen in other European countries, France now houses 10% of its herd outdoors, and Denmark and Sweden are conducting feasibility studies to determine if their cooler climates would permit

Two studies were conducted 1) to determine the effects of free fatty acid (FFA) concentrations and the degree of saturation of lipids (unsaturated to saturated fatty acids ratio [U:S]) on apparent total tract digestibility (ATTD) and DE content of lipids and 2) to derive prediction equations to estimate the DE content of lipids when added to lactating sow diets. In Exp. 1, 85 lactating sows were assigned randomly to a 4 × 5 factorial arrangement of treatments plus a control diet with no added lipid. Factors included 1) FFA concentrations of 0, 18, 36, and 54% and 2) U:S of 2.0, 2.8, 3.5, 4.2, and 4.9. Diets were corn-soybean meal based and lipid was supplemented at 6%. Concentrations of FFA and U:S were obtained by blending 4 lipid sources: choice white grease (CWG; FFA = 0.3% and U:S = 2.0), soybean oil (FFA = 0.1% and U:S = 5.5), CWG acid oil (FFA = 57.8% and U:S = 2.1), and soybean-cottonseed acid oil (FFA = 67.5% and U:S = 3.8). Titanium dioxide was added to diets (0.5%) as a digestibility marker. Treatments started on d 4 of lactation and fecal samples were collected after 6 d of adaptation to diets on a daily basis from d 10 to 13. The ATTD of added lipid and DE content of lipids were negatively affected (linear, < 0.001) with increasing FFA concentrations, but negative effects were less pronounced with increasing U:S (interaction, < 0.05). Coefficients of ATTD for the added lipid and DE content of lipids increased with increasing U:S (quadratic, = 0.001), but these improvements were less pronounced when the FFA concentration was less than 36%. Digestible energy content of added lipid was described by DE (kcal/kg) = [8,381 - (80.6 × FFA) + (0.4 × FFA) + (248.8 × U:S) - (28.1 × U:S) + (12.8 × FFA × U:S)] ( = 0.74). This prediction equation was validated in Exp. 2, in which 24 lactating sows were fed diets supplemented with 6% of either an animal-vegetable blend (A-V; FFA = 14.5% and U:S = 2.3) or CWG (FFA = 3.7% and U:S = 1.5) plus a control diet with no added lipids. Digestible energy content of A-V (8,317 and 8,127 kcal/kg for measured and predicted values, respectively) and CWG (8,452 and 8,468 kcal/kg for measured and predicted values, respectively) were accurately estimated using the proposed equation. The proposed equation involving FFA concentration and U:S resulted in highly accurate estimations of DE content (relative error, +0.2 to -2.3%) of commercial sources of lipids for lactating sows.

Forty Landrace × Large White lactating sows were used to evaluate the effects of cooling of the floor when maintained under high temperature conditions during summer on their productive and reproductive performance. The sows were allocated in a completely randomized design with two treatments with 20 replicates according to parity number and body weight, with each animal being considered an experimental unit. The treatments consisted of cooling of the floor under the sow with water circulation at about 17 °C and no cooling. The resulting temperatures of the floor were 27.6 and 35.8 °C for the cooled and the control treatments, respectively. The sows from both treatments were exposed to average maximum and minimum environmental temperatures of 26.9 and 20.8 °C, respectively. Sows maintained on a cooled floor had a higher feed intake (6.47 vs. 5.61 kg/day; P < 0.01). Despite this higher intake, sows maintained on a cooled floor had higher body weight and body protein losses during the lactation period (P < 0.01) in connection with a higher milk yield and subsequent growth of the litter (2280 vs. 1798 g/day; P < 0.01). There was an effect of treatment on rectal temperature, surface temperatures and respiratory rate (P < 0.01) with lower values in sows submitted to floor cooling. It is concluded that floor cooling under the lactating sow improves its productive and reproductive performance, as well as the performance of its litter.

To evaluate the behavioural effects of two feeding techniques, 30 lactating sows were allocated to two groups: T1 receiving a dry meal ad libitum offered for 30 minutes at fixed times (8:30 a.m. and 4:00 p.m.) and T2 in which sows received a liquid feed that was available from 6:00 a.m. to 11:00 p.m. T2 sows ate more feed (P0.05), the number and the body weight of piglets at weaning were higher for T2 sows. With regard to behavioural patterns, T2 sows spent more time standing and engaged in eating (P

We developed a simple, non-invasive method to measure the intramammary pressure (IMP) response in sows during natural milk ejection and after i.v. injections of oxytocin. The teats of sows were cannulated and the amplitude and duration of IMP changes were measured via a pressure transducer linked to a computer. During natural milk ejections, the amplitude of the response was 5·5±1·8 kPa (mean±SD) and the duration of response at half the peak amplitude was 6·8±1·6 s. In response to oxytocin a threshold response occurred at 60 mIU oxytocin with no further change up to 200 mIU. The amplitude of the response to an i.v. dose of 60–200 mIU oxytocin (5·5±2·2 kPa) and duration (6·4±1·7 s) were similar to that during a natural milk ejection. The responses of two galactophorous ducts of a teat measured simultaneously were similar in peak amplitude and duration. When the responses of four glands of a sow were measured simultaneously, there was a lag time in the onset of the IMP peak from the anterior to the posterior glands, and an increase in the peak amplitude from anterior to posterior. Both during natural milk ejections and in response to oxytocin injections, there were significant differences in peak amplitude between sows. We also aimed to determine whether the pressure or duration of milk flow during natural milk ejections was limiting piglet growth rates. IMP of nine sows and the growth rates of their piglets were measured. Both the peak amplitude of IMP response and the growth rate of piglets increased over the course of lactation, but the relationship was not causal. We found that the growth rate of piglets did not depend on IMP amplitude or duration, but we suggest that it may depend on the frequency of suckling and/or the ability of piglets to withdraw milk while it is available.

Vitamin A deficiency (VAD) is a public health problem affecting millions in developing nations. Supplementation for lactating women, whose needs are high, involves large oral doses of the preformed vitamin. The safety and efficacy of these doses has been inadequately studied. Lactating women typically receive 210 micro mol of retinyl ester during early lactation, but 420 micro mol has also been administered. If larger doses of vitamin A are not significantly more effective in preventing VAD in mothers and infants, then smaller doses would be recommended. We therefore examined the vitamin A concentration of milk from lactating sows (n = 15) that were provided two different doses of vitamin A (i.e., 1050 or 2100 micro mol, n = 6/group) or corn oil (n = 3), corresponding to doses given women on the basis of body weight. Compared with controls, an overall significant treatment effect was found (P = 0.0019), but there was no difference in milk concentration between treatment groups. Theoretically, applying the mean milk vitamin A concentrations of the groups through 12 h and values to 48 h from 4 sows, we estimate that an infant of a supplemented mother could realize an increase of +0.08 or 0.16 micro mol/g liver from the low or high dose, respectively.

The objective of this experiment was to evaluate the influence of glucose infusion during lactation on LH secretion in the energy- restricted sow. Ten primiparous Landrace x York- shire sows (152 kg postfarrowing) were fed a low- energy (6.5 Mcal of ME/d), high-lysine (45 g/dl, corn-soybean meal diet throughout lactation. On d 18 of lactation, sows received a continuous infu- sion (1 L/l2 h) of glucose (50% dextrose solution1 or .9% saline from 1200 to 2400. Blood samples were drawn every 15 min for an 18-h period on d 18 to evaluate concentrations of plasma glucose, serum insulin, and serum LH before (600 to 1200) and during (1215 to 24001 the infusions. The glucose infusion immediately increased (P e .001) plasma glucose and serum insulin relative to preinfusion levels. Glucose and insulin concentrations in sows receiving the glucose infusion were higher (P e .001) throughout the infusion period relative to concentrations in sows receiving a saline infusion. Glucose infusions had no influence on LH pulsatil- ity during the 12-h infusion period. In contrast to the response observed in the nutrient-restricted gilt, these results indicate that glucose infusions do not result in an immediate increase in pulsatile LH secretion in the energy-restricted, lactating sow. Key Words: Lactating Sows, Infusion, LH, Insulin, Glucose

Clinical and endocrinological responses to administration of gonadotropin releasing hormone analog (LH-RH-A) during the lactation period and postweaning in the sow were investigated. Plasma LH concentrations in lactating sows rose immediately after administration of LH-RH-A. However, in postweaning sows the increase of LH level was more slowly. Three of 5 postweaning sows came into estrus and ovulated after LH-RH-A treatment. One sow exhibited a distinct LH response, but her ovaries remained quiescent. The remaining one with feeble estrus for a short period became cystic ovaries. Thus, LH response to GnRH in the sow seems to be higher during early lactation than at 2 days postweaning.

Reproductive performance is steadily increasing within the pork industry; logically, amino acid requirements need to be redefined for sows producing larger litters. The objective of this study was to determine the threonine requirement of the high-producing lactating sow and to determine the effect of lysine on this requirement. A total of 419 PIC C-15 sows were assigned randomly to treatment within parity groups (1, 2, and 3+) and gestation treatment at d 110 of gestation. Lactation diets were formulated to contain 0.80% total lysine (tLYS) with 0.30, 0.35, 0.40, 0.45, 0.50, 0.55, 0.60, or 0.65% total threonine (tTHR) or 1.06% tLYS with 0.40, 0.45, 0.50, 0.55, 0.60, 0.65, or 0.70% tTHR. Litters were standardized to a minimum of 11 piglets within 48 h after farrowing, and sows had free access to feed throughout lactation (lactation length = 20.1 +/- 0.1 d). Sow ADFI exceeded expectation, averaging 6.90, 7.40, and 7.20 kg/d for Parities 1, 2, and 3+, respectively. Daily tLYS intake was 58 g/d (47 g of apparent ileal digestible lysine [dLYS] per day) and 74 g/d (59 g dLYS/d) for the low- and high-lysine group, respectively. Lysine intake did not affect sow or litter performance (P > 0.10). Sows gained an average of 4.8 kg in lactation. Using regression analysis, BW gain was maximized at 0.54% tTHR for all parity groups (quadratic; P < 0.05). Litter weaning weight (67.1, 67.9, and 66.2 kg for Parities 1, 2, and 3+, respectively) and litter weight gain (2.49, 2.53, and 2.44 kg/d for Parities 1, 2, and 3+, respectively) were maximized at 0.53% tTHR using regression analysis, for all parity groups (quadratic; P < 0.05). Based on regression analysis, plasma urea nitrogen on d 10 and 18 was minimized at 0.54% tTHR (P < 0.05). Lysine levels in excess of 58 g of tLYS/d did not benefit sow or litter performance. The requirement for threonine to minimize sow tissue mobilization was 37, 40, and 38 g tTHR/d (28, 30, and 30 g of apparent ileal digestible threonine [dTHR] per day) for Parities 1, 2, and 3+ sows, respectively. The threonine required to maximize litter performance was 36, 39, and 38 g of tTHR/d (28, 30, and 29 g of dTHR/d) for Parities 1, 2, and 3+ sows, respectively. Alternatively, the requirement can be expressed as 14.3 g tTHR (11.8 g dTHR) per kilogram of litter gain.

Effects of feeding frequency and addition of sugar to the diet for the lactating sow were investigated using 162 sows (10 replications) at four stations in the North Central Region. Sows were assigned to one of four treatments immediately after parturition (d 0). The four treatments were a corn-soybean meal diet (control) vs a similar diet containing 2.5% feed grade sucrose (sugar) and once vs thrice daily feeding. No feeding frequency x diet interactions (P greater than .10) were observed for any of the response criteria. Feed consumption and weight loss during lactation were not affected (P greater than .10) by treatments. Also, treatments had no effect (P greater than .10) on numbers of live pigs at parturition, pig survival or litter weight at d 21. The percentage of sows in estrus within 30 d after weaning was not affected (P greater than .10) by treatment. Of those sows that expressed estrus within 30 d postpartum, the weaning-to-estrus interval of sows fed sugar was 1.3 d shorter (P less than .05) than for sows fed the control diet. Neither feeding frequency nor addition of sugar to the diet affected feed consumption or reproductive performance of the sow during lactation. Because feed consumption and weight loss of the sow were not affected by diet, no reason for the slight reduction in the weaning-to-estrus interval of sows fed sugar is evident.