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The underconsumption of feed frequently observed in young sows during lactation can result from an adaptation problem of the sow to the new feeding management in terms of diet composition and feeding amount. Our study aimed to investigate how the sow manages her own feed transition when given the choice between the gestation diet and the lactation diet from moving into the farrowing crate (12 d before farrowing) until the second week postpartum. The effect of adding dietary fiber to the gestation diet on this transition was also evaluated. During gestation, 16 primiparous sows (Large White x Landrace) were fed 2.4 kg/d of a control (CON) diet (3.5% of crude fiber), or 2.9 kg/d of a high-fiber (HF) diet (12.8% of crude fiber). The daily allowance of NE was 24 MJ in both treatments. Twelve days before the expected parturition day (d -12), sows were moved into farrowing crates that were equipped with a computerized feeding device allowing the gestation and lactation diets to be supplied via 2 rewarded push buttons placed above the trough, until d 14 postpartum. The feeding transition was evaluated through the daily ratio of ingestion of the lactation diet. Feeding behavior was measured through daily feed and energy intakes, number of daily meals, meal size, and the nycthemeral distribution of feeding activity. Sows were weighed and backfat thickness was measured at the beginning and end of gestation and lactation. Piglets were weighed every week from birth until weaning. The transition to the lactation diet occurred earlier in HF sows (P < 0.05); the 50% threshold of lactation diet ingestion was reached on d -8 and 12 in HF and CON sows, respectively. Dietary treatment did not affect the feeding pattern, and all sows presented a diurnal feeding activity. During lactation, there was an interaction (P < 0.05) between the hour of the day and the dietary treatment for the distribution of pushes on the rewarded buttons, with pushes being more spread out throughout the day in CON sows compared with HF sows. Variations in sow backfat thickness were not affected by dietary treatment, but HF sows lost more BW during lactation (P < 0.05). Growth of piglets was not affected by dietary treatment. In conclusion, sows chose the lactation diet spontaneously on the week preceding parturition when they were fed a fibrous diet during gestation. This highlights the possible impact of such a gestation diet to promote early intake of the lactation diet. Key words: feeding behavior, fiber, free choice, primiparous, sow doi: 10.2527/jas.2009-2307

Voluntary feed intake of hyperprolific sows can be insufficient to cover the requirements for milk production and maintenance of body condition. A bulky diet fed during pregnancy is known to prepare sows for an ad libitum feed supply after parturition as shown by the increased feed intake during lactation. The aim of this study was to investigate the feeding behavior of young sows during their first lactation to evaluate the further impact of the feeding experience acquired during pregnancy, through the addition of dietary fiber in the diet. Analysis of the feeding pattern and the profile of feed intake tested the hypothesis that lactating sows would exhibit different feeding strategies depending on the diet during pregnancy. During pregnancy, 24 primiparous sows (Large White x Landrace) were offered either 2.4 kg of a control diet/d containing 3.16% crude fiber or 2.8 kg of a high-fiber diet/d containing 12.42% crude fiber. All sows received 33 MJ of DE/d. From the first day postpartum until weaning, all sows were offered the same lactation diet ad libitum. The feeding pattern during lactation was recorded as ADFI, meal frequency, and meal size. In lactation, the ADFI did not differ according to the treatment. Compared with control sows, high-fiber sows consumed their diet in more (P < 0.05) but smaller meals (P < 0.05). In both treatments, ADFI and the number of daily meals increased over weeks of lactation (P < 0.001). All sows presented a strong diurnal and bimodal feeding activity evolving toward 2 distinct feeding periods occurring from 0500 to 0900 and from 1400 to 1800 and accounting for 0.64 of the total daily feed intake during the third week of lactation. The provision of a fibrous diet during pregnancy pointed out the role of an early feeding experience on the development of feeding behavior during the first reproductive cycle. Key words: feeding behavior, fiber, lactation, primiparous, sow

A total of 120 crossbred [synthetic line x (Large White x Landrace)] pigs (castrated males and females) were used to evaluate the influence of rearing conditions for growing-finishing pigs on growth performance, carcass, stress reactions at slaughter, and meat eating quality. At approximately 35 kg of live weight (LW), littermates were allocated to either a conventional (fully slatted floor, 0.65 [m.sup.2]/pig, considered as control, CON) or an alternative (sawdust bedding with free access to an outdoor area, 2.4 [m.sup.2]/pig, OUT) system, until slaughter at approximately 110 kg of LW. Pigs had free access to standard growing and finishing diets. The trials were conducted in spring, summer, and winter, with each season involving 2 pens of 10 pigs in each system. Compared with the CON, the OUT pigs exhibited a greater growth rate (+10%, P < 0.001) due to their greater feed intake (+0.23 kg/d, P < 0.01), resulting in a greater body weight at slaughter (+7 kg, P < 0.001). The OUT pigs had thicker backfat (+2.4 mm, P < 0.01) and lower lean meat content (-2.0% points, P < 0.001) than the CON pigs. The OUT system did not (P > 0.10) influence the behavioral activities of pigs during lairage at the slaughterhouse, or the urinary levels of catecholamines and cortisol, and plasma levels of ACTH, cortisol, lactate, creatine kinase, and FFA immediately after slaughter. The OUT pigs had similar (P > 0.10) pH values 30 min postmortem (p[H.sub.1]) in the LM, biceps femoris (BF), and semimembranosus (SM) muscles, similar ultimate pH (p[H.sub.u]) in LM, but lower p[H.sub.u] in SM (-0.07 unit, P < 0.001) and in BF (-0.03 unit, P = 0.029). Despite nonsignificant effects of production system on stress reactions at slaughter, assessed by urine and plasma indicators and muscle metabolism at 30 min postmortem, meat from OUT pigs had more LM drip loss after 2 (+1.0%, P = 0.003) and 4 (+1.1%, P = 0.010) d than did meat from the CON pigs. The OUT system slightly increased meat yellowness (b* value) in the LM (+0.7 unit, P = 0.001), BF (+0.5 unit, P = 0.014), and SM (+0.5, unit P = 0.041), whereas redness (a*) and lightness (L*) of the 3 muscles were unaffected (P > 0.07). Intramuscular fat content was greater in the LM (+17%, P = 0.001), BF (+14%, P = 0.004), and SM (+17%, P = 0.003) of the OUT pigs. Outdoor rearing during summer and winter improved meat juiciness, whereas odor, flavor, and tenderness were unaffected (P > 0.10). Influence of rearing conditions on all the other traits studied did not depend on the season. Key words: behavior, hormone, housing, meat quality, muscle, pig

The possible roles of dietary protein level and feed restriction in regulating mammary development of prepubertal gilts were investigated. Crossbred gilts were fed a commercial diet until 90 d of age and then divided into four nutritional regimens based on two pelleted diets (as-fed basis): a high-protein diet (HP = 13.8 MJ of ME, 1.0% total lysine, 18.7% CP) and a low-protein diet (LP = 13.8 MJ of ME, 0.7% total lysine, 14.4% CP). Nutritional regimens were as follows: 1) HP ad libitum until slaughter (n = 22, T1); 2) HP ad libitum until 150 d of age followed by LP until slaughter (n = 20, T2); 3) LP ad libitum until slaughter (n = 21, T3); and 4) HP with a 20% feed restriction until slaughter (n = 19, T4). Gilts were weighed, their backfat thickness was measured, and jugular blood samples were obtained on d 90, 150, and at slaughter to determine concentrations of prolactin, IGF-I, leptin, and glucose. Gilts were slaughtered 8 [+ or -] 1 d after their first or second estrus (202.7 [+ or -] 14.5 d of age). Mammary glands were excised, parenchymal and extraparenchymal tissues were dissected, and composition of parenchymal tissue (protein, fat, DM, DNA, protein/DNA) was determined. The T4 gilts weighed less (P < 0.01) and had less backfat (P < 0.01) than did gilts on other treatments on d 150 and at slaughter. Treatments had no significant effects on prolactin, IGF-I, or glucose concentrations, but there was a treatment x day interaction (P < 0.01) for leptin, with concentrations being lower at slaughter in restricted-fed (T4) vs. LP (T3) gilts (P < 0.05). There was less extraparenchymal mammary tissue (P < 0.01) in T4 gilts than in gilts from the other groups and a tendency (P = 0.13) for the amount of parenchymal tissue to be lower in T4 gilts. In conclusion, a lower lysine intake during prepuberty did not hinder mammary development of gilts, but a 20% feed restriction decreased mass of parenchymal and extraparenchymal tissues. The effect of feed restriction on extraparenchymal tissue is most likely associated with the lower fat deposition. Key Words: Mammary Development, Mammary Glands, Pigs, Prepubertal Females, Protein Intake, Restricted Feeding

Two groups of three multiparous Large White x Landrace sows were used to investigate the direct effect of ambient temperature on mammary gland metabolism. Sows from the first group were exposed to temperatures of 28[degrees]C between d 8 and 14 of lactation, and 20[degrees]C between d 15 and 21; treatments were reversed in the second group. Four to six d after farrowing, an ultrasonic blood flow probe was implanted around the right external pudic artery and catheters were fitted in the right anterior mammary vein and in the carotid artery. After surgery all sows were fed 3.8 kg/d of a lactation diet. The arteriovenous (AV, mg/L) plasma samples were obtained every 30 min between 0915 and 1545 on d 5 of exposure to ambient temperature; the same day, milk samples were collected at 1630. Additional arterial samples were obtained between 1000 and 1100 on d 1, 4, and 6 of exposure. Milk yield was estimated from the body weight gain of the litter. Elevated temperature tended to reduce BW loss (2.44 vs 1.82 kg/d, P < 0.10), but did not affect milk yield (11.0 kg/d). Glucagon and leptin arterial concentrations increased (12 and 8%, respectively; P < 0.10), but thyroxin and triiodothyronine concentrations decreased (26 and 16%, respectively; P < 0.01) between 20 and 28[degrees]C. Expressed as a percentage of total nutrients, A--V difference, glucose, amino acids, triglycerides (TG), free fatty acids, and lactate A-V differences represented 60, 20, 11, 8, and 1%, respectively. Exposure to 28[degrees]C increased the extraction rate of glucose, TG, and [alpha]-amino acid N (13, 8, and 2.5%, respectively; P < 0.10). The extraction rates of essential and nonessential amino acids were not affected by temperature. The right pudic artery mammary blood flow increased (872 vs 945 mL/min, P < 0.05) between 20 and 28[degrees]C, whereas milk yield was unaffected by temperature. It is suggested that this apparent inefficiency of the sow mammary gland in hot conditions could be related to an increase of proportion of blood flow irrigating skin capillaries in order to dissipate body heat. Key Words: Mammary Glands, Milk Composition, Nutrient Uptake, Sows, Temperature

Low protein intake during lactation has been demonstrated to increase the loss of body protein and to reduce the reproductive performance of female pigs. The objectives of the current experiment were 1) to determine whether protein (lysine) restriction alters levels of somatotropic hormones, insulin, follicle-stimulating hormone, and leptin around weaning, and 2) to evaluate the relationships between these eventual alterations and postweaning reproductive performance. One day after farrowing, crossbred primiparous sows were randomly allocated to one of two diets containing 20% crude protein and 1.08% lysine (C, n = 12) or 10% crude protein and 0.50% lysine (L, n = 14) during a 28d lactation. Diets provided similar amounts of metabolizable energy (3.1 Mcal/kg). Feed allowance was restricted to 4.2 kg/d throughout lactation, and litter size was standardized to 10 per sow within 5 d after farrowing. Catheters were fitted in the jugular vein of 21 sows around d 22-of lactation. Serial blood samples were collected 1 d before (day W - 1) and 1 d after (day W + 1) weaning, and single blood samples were collected daily from weaning until d 6 postweaning (day W + 6). Sows were monitored for estrus and inseminated. They were slaughtered at d 30 of gestation. During lactation, litter weight gain was similar among treatment groups. Reduced protein intake increased (P < 0.001) sow weight loss (-30 vs -19 kg) and estimated protein mobilization throughout lactation (-4.1 vs -2.0 kg). On day W - 1, L sows had higher (P < 0.02) plasma glutamine and alanine concentrations, but lower (P < 0.05) plasma tryptophan and urea than C sows. Mean and basal plasma GH were higher (P < 0.001), whereas plasma IGF-I and mean insulin were lower in L than in C sows on day W - 1. Preprandial leptin did not differ between treatments on day W - 1, but was higher (P < 0.01) in L sows than in C sows on day W + 1. Mean FSH concentrations were similar in both treatments on day W - 1 (1.3 ng/mL), but L sows had greater (P < 0.001) mean FSH on day W + 1 than C sows (1.6 vs 1.2 ng/mL). The weaning-to-estrus interval (5 [+ or -] 1 d) was similar in both groups. Ovulation rate was lower in L than in C sows (20.0 [+ or -] 1 vs 23.4 [+ or -] 1, P < 0.05). No obvious relationships between reproductive traits and metabolic hormone data were observed. In conclusion, these results provide evidence that protein (lysine) restriction throughout lactation alters circulating concentrations of somatotropic hormones and insulin at the end of lactation and has a negative impact on postweaning ovulation rate. Key Words: Insulin-Like Growth Factor, Lactation, Metabolism, Protein Intake, Reproduction, Sows

Two experiments were conducted to determine the lysine and threonine requirements of gestating sows. In the first experiment, four levels of lysine (0.34, 0.42, 0.48, and 0.56% crude lysine, and 0.24, 0.31, 0.38, and 0.45% standardized ileal digestible lysine) were compared in eight multiparous Large White sows. Each sow received successively the four diets according to a Latin-square experimental design. Nitrogen balance was measured over 11 d after a 10-d period of adaptation to the experimental diet. In the second experiment, four threonine/lysine ratios (0.63, 0.73, 0.80, and 0.89 on a crude basis and 0.61, 0.71, 0.77, and 0.87 on a standardized ileal digestible amino acid basis) were compared in 16 multiparous sows, according to a Latin-square experimental design. The standardized ileal digestibility of amino acids in the experimental diets was determined with ileo-rectal anastomized growing pigs. In the first experiment, nitrogen retention was affected by lysine supply (linear, P < 0.001; quadratic, P < 0.04). Nitrogen retention was lowest for treatment 1 (8.0 g/ d) and highest for treatments 3 and 4 that did not differ. Nitrogen retention plateaued at 14.7 g/d in sows consuming 10.5 g/d of digestible lysine. The maintenance requirement for digestible lysine was calculated to be 27 mg/kg B[W.sup.0.76] with an efficiency of utilization of digestible lysine above maintenance at 59%. In the second experiment, nitrogen retention was affected (P < 0.03) by the threonine:lysine ratio. It was lower for the lowest threonine:lysine ratio (0.63) than for the other three treatments that did not differ among each other. These results indicate that the optimal standardized digestible threonine:lysine ratio appears to be about 0.71 for multiparous gestating sows. Key Words: Lysine, Nitrogen Retention, Pregnancy, Sows, Threonine

Two replicates of three multiparous crossbred Large White x Landrace lactating sows were used to develop a technique for the continuous direct measurement of the blood flow through the mammary gland using transit time ultrasound. Four to six days after farrowing, an ultrasonic transit time flow probe was implanted around the right external pudic artery in order to measure the short-term variations of mammary blood flow through this vessel in response to postural change (standing vs lying), meal distribution, hand-milking, and weaning. After surgery, all sows were fed 3.8 kg/d of a lactation diet and housed either at 20 or 28 [degrees] C. The implantation of the ultrasonic blood flow probe was successful in all six operated sows. Postmortem examination did not indicate the presence of infection, any collateral bypassing the flow probe, or a reduction of artery diameter. The right pudic artery mammary blood flow (PMBF) was measured for 8.5 h over two periods of three days (d 11 to d 13 and d 18 to d 20 of lactation). The PMBF averaged 910 [+ or -] 238 mL/min but was variable within 1 d. Compared with the lying position, PMBF was decreased (- 6%, P < 0.05) when sows were standing. Between 0 to 15 and 16 to 30 min after oxytocin injection (t = 0) and hand-milking, PMBF remained constant (P = 0.05; 801 vs 767 mL/ min) and increased (P = 0.02), respectively, in comparison with the mean calculated over the preceding 30-min period (982 vs 784 mL/min). The PMBF increased (P < 0.05) after meal distribution and reached a peak 65 min later (i.e., 980 mL/min). The PMBF decreased regularly after separation of piglets at weaning; at 8 and 16 h after weaning, PMBF was 60 and 40% of the value recorded before weaning, respectively. Assuming that PMBF drains one-quarter of the whole mammary gland, it can be calculated that blood flow through the entire mammary gland averages 3.6 L/min and that about 470 L of blood are required to produce 1 kg of milk. The proposed methodology constitutes a new technique to measure direct mammary blood flow and its short-term factors of variation. Key Words: Blood Flow, Lactation, Mammary Glands, Sows

Twelve pregnant, multiparous sows were assigned during gestation to three dietary treatments in a 3 x 3 Latin square design to evaluate the effect of increasing levels of crude fiber (CF): a conventional diet low in CF (L, 15.8 MJ DE/kg of DM, 3.3% CF), a diet with a medium level of CF (M, 14.4 MJ DE/kg of DM, 10.6% CF), and a high-fiber diet (H, 12.9 MJ DE/kg of DM, 18.1% CF). The daily feed supply was adjusted to provide the same 33.4 MJ of daily digestible energy (2.4, 2.7, and 3.0 kg/d for diets L, M, and H, respectively). Over the day, a shorter time standing was spent when sows received the H diet (291 min/d) compared with the L (363 min/d) and M diets (324 min/d). Duration of feeding was longer with the high-fiber diet. Mastication represented the main part of the feeding activity in sows fed the H diet (56%) and was reduced with the M and L diets (40% and 25%, respectively). Feeding rate increased when fiber level decreased (67, 120, and 152 g/min for the H, M, and L diets, respectively). Feeding the fibrous diet reduced the incidence of nonfeeding oral behaviors. These results show that high-fiber diets can reduce apparent feeding motivation of pregnant sows and, thus, improve the welfare of sows subjected to feed restriction. Key Words: Sows, Nutrition, Fiber, Behavior, Animal Welfare

Using 73 Large White gilts, we studied the lysine requirement during lactation. Sow and pig performance and nitrogen balance of sows were measured during the total 21-d lactation period. Variation in body composition of sows between farrowing and weaning was determined by the comparative slaughter technique. Two levels of crude protein (15.5 and 17.1%) were combined with two levels of L-lysine HCl supplementation (0 and. 16%), resulting in four diets termed P1L1, P1L2, P2L2, and P2L3, containing .66, .77, .77, and .87% crude lysine, and 15.5, 15.5, 17.1, and 17.1% crude protein, respectively. Sows' feed intake, litter growth rate, and milk energy and protein output were not affected by the diet. Nitrogen balance over the total lactation increased (P < .001) with an increase in lysine and(or) protein (-11.7, -7.0, -3.4, and .4 g N/d for P1L1, P1L2, P2L2, and P2L3 diets, respectively). The losses of body weight and muscle weight were higher in P1L1 gilts (P < .01 and .05, respectively) than in gilts on other treatments, whereas the loss of adipose tissue and backfat was similar for the four groups. Multiple linear relationships between lysine intake and milk nitrogen output as predictors and nitrogen balance (N balance = -15.8 + 1.22 lysine - .63 N milk, [R.sup.2] = .89) or variation of muscle weight (Vm = -477 + 30.1 lysine - 14.7 N milk, [R.sup.2] = .70) as predicted values were calculated to estimate lysine requirement according to production performance of sows. Calculations show that for achieving a zero protein balance, 45 to 55 g/d of crude lysine are required for normal to high-yielding sows, respectively. Key Words: Sows, Lactation, Lysine, Requirements, Protein

Measurements of heat production(HP; indirect calorimetry) and its partition between maintenance, physical activity, thermoregulation, and thermic effect of feed or energy gain were carried out in sows maintained in different situations: primiparous or multiparous; pregnant or nonpregnant; thermoneutral or cold conditions; varied feeding levels; and varied body weights (BW). Metabolizable energy requirements for maintenance average 420 kJ/kg [BW.sup..75] at thermoneutrality and moderate physical activity. This value is not significantly affected by parity, pregnancy, and stage of pregnancy. Physical activity is a major factor causing differences in energy balance between sows because activity is variable and its energy cost (27 kJ.kg [BW.sup.-.75][multiplied by]100 [min.sup.-1] standing) is four to five times higher than in other species. Lower critical temperature (LCT) is approximately 20 [degrees] C in pregnant and individually housed sows, and daily HP is increased by approximately 15 kJ/kg [BW.sup..75] for each degree Celsius decrease of ambient temperature below LCT. Efficiencies of utilization of ME for meeting energy requirements for maintenance, maternal gain, and uterine gain are 77, 75, and 50%, respectively. Equations for predicting energy deposition in the uterus and mammary gland are proposed. In addition to activity and thermoregulation, energy requirements of pregnant sows depend on body reserves of energy. Studies with newborn pigs indicate that they are quite sensitive to ambient temperature (i.e., +25 J[multiplied by]kg [BW.sup.-.75][multiplied by][min.sup.-1] for each degree Celsius decrease of temperature), and their LCT is 32 to 34 [degrees] C. The energy demand of pigs for thermoregulation just after birth relies mainly on carbohydrates from glycogen reserves or colostrum. Survival of newborn pigs is highly dependent on the supply of colostrum. Key Words: Sow Pregnancy, Neonates, Pigs, Energy Metabolism

Multiparous Large White sows were used in two experiments to determine the effects of energy intake on the reconstitution of body reserves during pregnancy. In Exp. 1, 21 sows received one of three different energy levels during pregnancy: 7.4, 8.8, or 10.4 Mcal DE/d. In Exp. 2, two energy levels (7.9 and 9.2 Mcal DE/d) were fed to 36 sows that mobilized low or high amounts of body reserves during the previous lactation (6 or 12 pigs per litter, respectively). Nitrogen balances were conducted during five 7-d periods at 11, 32, 53, 82, and 104 d of gestation. All the experimental sows were slaughtered and dissected at the end of pregnancy; 24 control sows were similarly slaughtered at mating in order to estimate composition of BW gain, according to the comparative slaughter technique. In the two experiments, average nitrogen (N) retention increased linearly with energy supply from 9.9 to 14.5 g/d in Exp. 1 (P < .001) and from 10.2 to 12.5 g/d in Exp. 2 (P < .05). Nitrogen retention was not affected by the extent of mobilization of body reserves during the previous lactation in Exp. 2. In both experiments, carcass weight (P < .001), muscle weight (P < .01), and dissectable fat weight (P < .001, Exp. 1; P < .01, Exp. 2) increased with energy supply. We conclude that in high-producing modern multiparous sows, energy supply during gestation is a limiting factor for N retention and muscle weight gain and should be approximately 8,500 kcal DE/d to ensure adequate restoration of body reserves. Key Words: Sows, Pregnancy, Nitrogen, Energy Intake, Body Condition

Primiparous Large White females were exposed to one of two light regimens characterized by an increase (from 12 to 16 h/d, LONG treatment) or a decrease (from 12 to 8 h/d, SHORT treatment) in photoperiod during gestation. Two successive replicates were conducted, and farrowings occurred in January and July. During the last month of gestation, during lactation and after weaning, ambient temperatures varied between 18 and 25 [degrees] C and between 25 and 38 [degrees] C for the first and second replicates, respectively. Weaning occurred at 3 wk postpartum. Percentage of sows in estrus within 10 d after weaning was higher (P [is less than] .05) in the SHORT than in the LONG group for both replicates and when farrowing occurred in January compared with July for both photoperiod groups (SHORT-January: 92%, LONG-January: 53%, SHORT-July: 32%, LONG-July: 14%). Loss of live weight in sows during lactation was higher in July than in January and higher in the SHORT than in the LONG photoperiod (P [is less than] .05). Live weight of pigs at birth was higher in July than in January, whereas growth rate of pigs until weaning was higher in January (P [is less than] .05). Temperature may have a greater influence on sow and litter performance than photoperiod.