Effect of litter birth weight standardization before first suckling on colostrum intake, passive immunization, pre-weaning survival, and growth of the piglets.

Within-litter variation in birth weight is a relevant factor in pig production. This study aimed at comparing pre-weaning mortality, colostrum intake (CI), passive immunization, and growth of piglets from litters of uniform (UN) or heterogeneous (HET) birth weights. The study included 52 multiparous sows (Large White × Landrace) and their litters. Two types of litters were constituted based on birth weight, namely: UN or HET, the control group, using piglets from two to three sows farrowing approximately at the same time. At birth, piglets were weighed, identified, and placed in a box under an IR lamp. At the end of farrowing, piglets were re-weighed and allotted to groups UN or HET (12 per litter) with average weights of 1394 and 1390 g, respectively, and allowed to suckle (time 0). They were re-weighed 24 h later to estimate CI and sows' colostrum yield. At time 0, the average intra-litter CV (%) in weight of experimental litters were 9.3 ±â€¯0.8 (SEM) and 27.8 ±â€¯0.7 in groups UN and HET, respectively (P < 0.001). At 2 days of age, blood samples were taken from the piglets of 11 litters five UN and six HET) and serum Immunoglobulin G (IgG) contents were determined. Mean CI/piglet/litter was similar in both groups, that is, 415 ±â€¯13 in UN and 395 ±â€¯13 g in HET (P = 0.28), but was less variable in UN litters (CV = 22.4 ±â€¯2 vs 36.0 ±â€¯2%, P < 0.001). The IgG levels at 2 days of age were higher in piglets from UN litters (22.5 ±â€¯0.8 vs 18.4 ±â€¯0.7 g/l; P < 0.001) but the CV of IgG levels was not different between litter type (P= 0.46). Mortality up to 21 days of age was lower in UN litters (6.4 vs 11.9%, P = 0.03). The BW at 21 days was not different between litter type (P = 0.25) but it was less variable among piglets from UN litters (CV: 17.1 ±â€¯1.3 vs 25.7 ±â€¯1.3%; P = 0.01). Results reveal that CI is less variable and mortality is lower in piglets from litters of UN birth weight. The results infer that genetic improvement to decrease variation in birth weight within-litter could have a positive effect on homogeneous CI and thus contribute to reducing piglet mortality.

Improvement of growth performance and sanitary status of weaned piglets fed a bovine colostrum-supplemented diet.

The present study investigated the effect of 3 different durations of feeding a diet supplemented with defatted bovine colostrum (Col) on growth performance and sanitary status of the weaned piglet. At 28 d of age, piglets were weaned and fed 1 of the 2 following diets: a control (Ctrl) starter diet or a starter diet supplemented with Col. Two experiments were conducted. In Exp. 1, 310 piglets (12 pens consisting of 10 piglets/pen and 10 pens consisting of 19 piglets/pen) were allocated to 1 of the 2 dietary treatments for 12 d. In Exp. 2, 522 piglets (18 pens consisting of 10 piglets/pen and 18 pens consisting of 19 piglets/pen) were allocated to 1 of the following 3 dietary treatments: fed the Ctrl diet from d 1 to 12 (Ctrl), Col diet from d 1 to 4 and then the Ctrl diet up to d 12 (Col-4d), or the Col diet from d 1 to 6 and then the Ctrl diet up to d 12 (Col-6d). For both experiments, a commercial second-phase diet was fed to piglets from d 12 to 46. Feed intake, growth performance, and cleanliness of floor and hindquarters of animals were investigated during the first 7 wk postweaning. In Exp. 1, from d 0 to 12, ADFI, ADG, and G:F were 16 (P = 0.004), 23 (P < 0.001), and 5% (P = 0.069) greater, respectively, in Col piglets compared with Ctrl piglets. Thereafter, ADFI and ADG were 7 (P < 0.001) and 9% (P < 0.001) greater, respectively, in Col piglets than Ctrl piglets (d 12 to 46). On d 12 after weaning, piglets fed the Col diet had more normal feces (+13%) and less soft or liquid feces (-9 and -4%, respectively) than piglets fed the Ctrl diet (P = 0.06). Compared with Ctrl piglets, feeding the Col diet led to more days with normal feces for the floor cleanliness (+22%; P < 0.001) from d 7 to 11. In Exp. 2, compared with Ctrl piglets, ADFI, ADG, and G:F were 8, 23, and 13% greater (P < 0.05) in Col-6d piglets from d 0 to 9, whereas values for Col-4d piglets were intermediate and did not differ from the values of the other dietary treatments. On d 9 after weaning, piglets fed the Col-4d or the Col-6d diet had more normal feces (+6 and +4%, respectively) and less liquid feces (-4 and -3%, respectively) than piglets fed the Ctrl diet (P = 0.08). No long lasting effects were observed thereafter. In conclusion, there was a reduction of weaning-induced growth check and diarrheal episodes in weaned piglets fed the Col diet. The beneficial effects of the bovine colostrum were observed beyond the period of treatment when the supplementation covered the first 6 d postweaning, which corresponded to the acute phase of postweaning digestive disturbances.

Influence of colostrum intake on piglet survival and immunity.

Colostrum intake from birth to 24 h after the onset of parturition (T24) was estimated for 526 piglets from 40 litters. Plasma concentrations of immunoglobulin G (IgG), lactate, glucose and cortisol were determined at T24 for six piglets per litter. Plasma IgG concentration was also assayed at weaning (28 days) on the same piglets. Rectal temperature was measured at T24 on all piglets. Mortality was recorded until weaning and comparisons were made between piglets that died before weaning and those that were still alive at weaning. The piglets that died before weaning had lower birth weight, lower colostrum intake, lower weight gain between birth and T24, and had a lower rectal temperature, higher plasma cortisol concentration and lower plasma IgG and glucose concentrations at T24 than piglets still alive at weaning. In addition, a higher proportion of piglets that died before weaning had difficulty taking their first breath after birth and were affected by splayleg. Considering all piglets, colostrum intake was positively related to rectal temperature and plasma glucose concentration and negatively related to plasma cortisol concentration at T24. Plasma IgG concentration at T24 was explained by colostrum intake, IgG concentration in the ingested colostrum, birth weight and birth rank (P<0.0001). Plasma IgG concentration at weaning was related to plasma IgG concentration at T24 (r=0.54; P<0.0001) and to colostrum intake (r=0.32; P<0.0001). Finally, body weight was explained by colostrum intake, birth weight and age until 6 weeks of age (P<0.0001). These results show that colostrum intake is the main determinant of piglet survival through provision of energy and immune protection and has potential long-term effects on piglet growth and immunity.

Effect of organic and inorganic selenium sources in sow diets on colostrum production and piglet response to a poor sanitary environment after weaning.

The objectives of this study were to determine the effect of the chemical form of selenium (Se) fed to sows (1) on production and immune quality of colostrum and (2) on piglet response to a deterioration of sanitary conditions after weaning. Twenty-two pregnant sows were assigned to receive a diet supplemented with 0.3 ppm Se from either sodium selenite (inorganic Se) or Se-enriched yeast (organic Se as Sel-Plex®; Alltech Inc., Nicholasville, KY, USA). Dietary treatments were applied during the last month of pregnancy and lactation. Blood samples were collected on sows before dietary treatment, on the day of weaning and 6 weeks later, and on three to five piglets within litters at birth, at weaning and 6 weeks post weaning. Whole blood was analysed for Se concentration. Colostrum samples were collected at 0, 3, 6 and 24 h post partum and milk samples on days 14 and 27 of lactation. Colostrum and milk were analysed for Se and immunoglobulin G (IgG) concentrations. At weaning, 40 pairs of littermate piglets were moved to rooms where sanitary conditions were good or purposely deteriorated. Piglets were reared individually and fed ad libitum. After 15 days, piglets and feed refusals were weighed and a blood sample was collected to measure plasma haptoglobin concentration. When sows were fed organic Se, Se concentrations were increased by 33% in colostrum (P < 0.05), 89% in milk (P < 0.001) and by 28% in whole blood of piglets at weaning (P < 0.001). Colostrum production during the 24 h after the onset of farrowing and IgG concentrations in colostrum and milk did not significantly differ between the two groups of sows. Weaned piglets reared in good sanitary conditions grew faster (P < 0.001) than piglets housed in poor conditions. Sanitary conditions did not influence mean plasma haptoglobin concentrations of piglets (P > 0.1). The source of Se fed to the dams did not influence piglet performance or haptoglobin concentrations after weaning. These findings confirm that, compared with inorganic Se, organic Se fed to the dam is better transferred to colostrum and milk, and consequently to piglets. They indicate that the Se source influences neither colostrum production nor IgG concentrations in colostrum, and that the higher Se contents of piglets does not limit the reduction of growth performance when weaning occurs in experimentally deteriorated sanitary conditions.

Variability of colostrum yield and colostrum intake in pigs.

Colostrum yield and composition of 40 Landrace×Large White sows were determined from the onset of parturition until 24 h post partum. Colostrum yield was calculated by adding individual piglets' colostrum intakes for each litter. Colostrum was assayed for prolactin, progesterone, oestradiol-17ß, immunoglobulin G and its nutritional composition was determined. Piglets' individual colostrum intake averaged 300 ± 7 g and sows' colostrum yield averaged 3.67 ± 0.14 kg (minimum 1.91 kg, maximum 5.31 kg). Live weight and characteristics at birth (umbilical cord already ruptured, splayleg, difficulty to breathe) were the major factors influencing individual colostrum intake. Colostrum yield was not affected by litter size, tended to be influenced by parity (P = 0.059) and was lower when farrowing was induced (P = 0.017). On the other hand, no relationships were found between hormone concentrations in colostrum and colostrum yield. Mean piglet birth weight and litter weight variation at birth were related to colostrum yield (r = 0.38; P = 0.015 and r = -0.34; P = 0.030, respectively). These results suggest that determinism of colostrum yield depends, in part, on global vitality of the litter but seems to be, most probably, affected by the capacity of sows to produce enough colostrum for the whole litter. Further studies are needed to understand the endocrine regulation of colostrum secretion in sows.

Estimation of genetic trends from 1977 to 1998 of body composition and physiological state of Large White pigs at birth.

Genetic trends for body composition and blood plasma parameters of newborn piglets were estimated through the comparison of two groups of pigs (G77 and G98, respectively) produced by inseminating Large White (LW) sows with semen from LW boars born either in 1977 or in 1998. Random samples of 18 G77 and 19 G98 newborn piglets were used for whole carcass and tissue sampling. Plasma concentrations of glucose, albumin and IGF-1 were determined on 75 G77 and 90 G98 piglets from 18 litters. The G98 piglets had less carcass dry matter, protein and energy (P < 0.01) than their G77 counterparts. When expressed in g/kg birth weight, livers were lighter (P < 0.001) and contained less glycogen (P < 0.01) in G98 piglets, with no difference in the activity of the hepatic glucose-6-phosphatase between G98 and G77 piglets. Concentrations of protein, DNA, RNA in longissimus dorsi muscle were unaffected by selection. Plasma concentrations of glucose (P < 0.05) and IGF-1 (P < 0.01) were lower in G98 than in G77 piglets. On the whole, the results suggest that the improvement in lean growth rate and in sow prolificacy from 1977 to 1998 has resulted in a lower maturity of piglets at birth.

Neuroendocrine consequences of very early weaning in swine.

An experiment was conducted to investigate the consequences of very early weaning of piglets on neuroendocrine variables and growth. Sixty piglets from eight litters were either weaned on Postnatal Day 6 (early weaning, or EW piglets) or left with their dam until normal weaning at Day 28 (control piglets, or C). At Days 5, 7, 11, 14, and 19, urine was collected between 7:00 and 8:00 a.m. for the measurement of catecholamines, glucocorticoids, and creatinine. Compared with C, EW piglets displayed a transient increase in urinary cortisol on the day following separation from their dam (Day 7) (P<.05). Urinary norepinephrine (NE) was three times lower in EW compared to C piglets from Day 7 until Day 14 (P<.01) but there was no difference between the two groups on Day 19. Urinary epinephrine (EPI) did not differ between C and EW piglets on the day after weaning. Thereafter, EW piglets displayed a three times drop in urinary EPI as compared to C piglets until the end of the period (P<.01). Weaning induced an immediate reduction in food intake and growth rate and at Day 28, the body weight of EW piglets was 1.60 kg lower than that of C piglets (P<.0001). In conclusion, weaning of 6-day-old piglets results in a marked and prolonged suppression of the release of catecholamines. This result likely reflects physiological responses to insufficient energy intake after weaning, as reflected also by changes in thermoregulatory behavior. The transient increase in cortisol excretion in weanlings may be caused by both emotional distress and acute food deprivation.

Effect of oxygen inhalation at birth on the reduction of early postnatal mortality in pigs.

Asphyxia during delivery is considered a main cause of stillbirth in pigs, but piglets suffering from intermittent asphyxia during delivery are also less viable at birth and less prone to adapt to extrauterine life. In an effort to improve pig viability, one attractive solution would be to increase oxygen supply through oxygen inhalation by the newborn pig. The objective of this study was to test effects of oxygen inhalation immediately after birth on various physiological parameters and piglet survival. The experiment was performed on 252 Piétrain x Large White piglets, half of them reoxygenated immediately after birth. They were maintained during 20 min in a chamber where oxygen concentration was monitored at 40% and were then put back with the sow and the control pigs. Oxygen inhalation affected piglet metabolism. Through stimulation of oxidative metabolism (reduction of circulating levels of lactate) and lowering of the level of postnatal hypothermia (particularly for the lightest pigs), oxygen inhalation increased piglet viability and reduced mortality during the 1st d of life by 75% (2 vs 8%). No additional effects were observed during the following days and overall mortality between birth and weaning at 21 d was reduced from 12 to 8%.

Influence of a high ambient temperature on lipid metabolism in the growing pig.

Because pigs are fatter when they are heat-stressed, it was hypothesized that lipid metabolism is enhanced in heat-stressed pigs. To test this hypothesis, an experiment was conducted to determine the influence of a high ambient temperature on the level of plasma lipids, thyroid hormones, lipoprotein lipase activity, and on the composition of very low density lipoproteins (VLDL) and chylomicrons in the growing pig. Twelve Large White x Landrace castrated male pigs with an initial weight of 20 +/- 0.6 kg were allotted to one of the following treatments: 1) ambient temperature of 31 degrees C, with ad libitum access to feed or 2) ambient temperature of 20 degrees C and fed the amount consumed by those kept at 31 degrees C until 35 kg BW. Ambient temperature did not affect piglet performance. Compared to that in pigs kept at 20 degrees C, in pigs kept at 31 degrees C the lipid content of backfat was 26% higher and the proportion of flare fat was increased by more than twofold (P < 0.001). Lipoprotein lipase activity was increased more than twofold in backfat and nearly twofold in leaf fat at 31 vs 20 degrees C (P < 0.001). In warmth-exposed (31 degrees C), feed-restricted pigs, the plasma level of triiodothyronine was 30% lower than at 20 degrees C (P < 0.001), whereas VLDL-lipid concentration was more than fourfold higher, and plasma concentrations of NEFA and triglycerides were 2.6- and 3.6-fold higher, respectively (P < 0.001). In conclusion, the chronic exposure of growing pigs to a high ambient temperature enhances lipid metabolism in both the liver (VLDL production) and the adipose tissue (lipoprotein lipase activity). Consequently, plasma triglyceride uptake and storage are facilitated in the adipose tissue, which results in greater fatness.

Behavioural, growth and immune consequences of early weaning in one-week-old large-white piglets.

Genetic improvement in sows' prolificity is limited by their milk capacities, which do not allow all piglets to survive or grow normally. This experiment compared the behaviour, growth and immune responses of piglets that were weaned early at 6 days of age (EW) vs. control Large White piglets' (C) suckled by their mothers. Behaviour of 9 litters of 5 to 8 piglets in each group were observed from d5 to d20. All piglets were weighed from birth to d74. Three piglets from each group were slaughtered on d36 for immunological analysis. Until they began to eat dry food, EW piglets walked and vocalised more than C piglets. After that time, when resting, they were less often lying down and more frequently in contact with littermates under the heater. Aggressive behaviour and belly-nosing were more frequent. They displayed a more marked growth check after weaning than did C piglets until 28 days of age. In EW piglets, at 36 days of age, there was a higher density of T- and B-lymphocytes in the gut epithelium and lamina propria, fespectively, in relation to the size of lymphoid follicles of Peyer's patches. The results indicate great behavioural adaptation capacities of very early-weaned piglets, together with earlier maturation of their gut immune system.

Lipogenic enzyme activities in subcutaneous adipose tissue and skeletal muscle from neonatal pigs consuming maternal or formula milk.

The influence of maternal and formula milk on lipid metabolism was studied in 7-day-old pigs. Lipid content, fatty acid composition, lipogenic enzyme activities and expression of GLUT4 mRNA were determined in subcutaneous adipose tissue and skeletal muscle from pigs that were bottle-fed formula milk (F) or sow milk (SM), or were sow-reared (SR). Bottle-fed pigs were isoenergetically fed and achieved similar daily body weight gain. SR pigs have a higher (P < 0.05) body weight gain than bottle-fed pigs. Lipid content of adipose tissue was lower (P < 0.05) in F than in SM and SR pigs. In muscle, lipid content did not differ significantly between groups. In adipose tissue, acetyl-CoA-carboxylase (CBX), fatty acid synthase (FAS), malic enzyme (ME), glucose-6-phosphate-dehydrogenase (G6PDH) and lipoprotein lipase (LPL) activities and GLUT4 mRNA levels were higher (P < 0.05) in SR than in bottle-fed pigs. In muscle, ME and G6PDH activities and GLUT4 mRNA were higher (P < 0.05) in F than in SM and SR pigs; LPL was not detected. The present study indicates that lipogenic enzyme activities and GLUT4 mRNA expression are regulated differently in subcutaneous adipose tissue and skeletal muscle in the neonatal pig.

Proliferation and differentiation of stromal-vascular cells in primary culture differ between neonatal pigs consuming maternal or formula milk.

Proliferation and differentiation of preadipocytes from 7-d-old pigs consuming maternal or formula milk were examined in primary culture of stromal-vascular (s-v) cells derived from subcutaneous adipose tissue. Unsuckled pigs were bottle-fed isoenergetically with colostrum and then sow's milk (SM) or with formula milk alone (F) from birth to 7 d. Isolated cells were exposed to serum-supplemented medium and serum-free medium to determine proliferation and differentiation, respectively. Proliferation estimated between d 3 and 4 of culture was higher (P<0.05) in cells from F than SM pigs. In addition, the number of s-v cells isolated from 1 g of adipose tissue was higher (P<0.01) in F than SM pigs. Variables assessing differentiation were also affected. The percentage of differentiating cells and lipoprotein lipase (LPL) activity were lower (P<0.05) in F than SM pigs, whereas malic enzyme (ME) activity did not differ significantly between the two groups. In conclusion, formula milk increased the number of s-v cells and their capacity for proliferation, whereas the potential for cell differentiation was lower compared with cells from the maternal milk group. Further studies are required to identify the growth and/or nutritional factors that are implicated in the observed differences and to determine whether subsequent development of adipose tissue is affected.

Influence of a high ambient temperature on stearoyl-CoA-desaturase activity in the growing pig.

An experiment was conducted to determine the influence of a high ambient temperature on the stearoyl-CoA-desaturase activity and fatty acid composition of backfat, leaf fat, Longissimus dorsi muscle and liver, in the growing pig. Eighteen Large White X Landrace castrated pigs (20 kg body weight) were divided into three groups: I (31 degrees C, ad libitum), II (20 degrees C, pair-fed on the 31 degrees C group) and III (20 degrees C, ad libitum) until 35 kg body weight. At 20 degrees C, the level of feed intake had no effect on stearoyl-CoA-desaturase activity, whatever the tissue (groups II and III). At similar levels of feeding, (groups I and II), the stearoyl-CoA-desaturase activity was lower at 31 degrees C (P < 0.001) than at 20 degrees C, regardless of the tissue, with the exception of the hepatic stearoyl-CoA-desaturase activity, which was similar in all three groups. This reduction of the stearoyl-CoA-desaturase activity at 31 degrees C could be related to a decrease in the monounsaturated fatty acid percentage in all the tissues, in hot conditions. The present results show that changes in fatty acid composition caused by environmental temperature, in the pig, may be attributed at least in part to an alteration in the stearoyl-CoA-desaturase activity.

Effects of acute asphyxia at birth on subsequent heat production capacity in newborn pigs.

The effect of acute asphyxia at birth on subsequent ability to produce heat was investigated in 30 newborn pigs. A model of experimentally induced asphyxia consisting of the prevention of breathing within the first four minutes of life was used. Blood was sampled from an umbilical artery catheter within the first 75 minutes of life for blood gas, pH, glucose, lactate and catecholamine analysis. After the treatment and 24 hours later, heat production capacity, shivering intensity and rectal temperature were measured 10 degrees C below thermoneutrality. Effects on blood gas parameters were severe but transient whereas alterations in carbohydrate metabolism were maintained during the first 75 minutes (P < 0.05). Acute asphyxia at birth induced only minor alterations of thermoregulatory abilities during the first day of life: rectal temperature was lower one hour after birth (P < 0.05) and the postnatal increase in heat production capacity was less pronounced than in controls. It is suggested that the lower viability usually reported for piglets suffering from asphyxia during delivery is most likely to result from reduced vigour and colostrum intake, as well as altered carbohydrate metabolism early after birth.

Thermoregulatory responses of the newborn pig during experimentally induced hypothermia and rewarming.

Exposure to a temperature of 14 degrees C was used to induce a progressive hypothermia in fourteen conscious newborn piglets. Heat production, body (rectal) and skin (between the shoulders) temperatures and shivering intensity assessed as the electromyographic activity (EMG) of longissimus thoracis muscle were measured until body temperature reached 30 degrees C and during a recovery period of 2 h at an ambient temperature of 24 degrees C (n = 7) or 34 degrees C (n = 7). During body cooling, heat production increased up to 9.67 +/- 1.28 W (kg BW)-1, but started to decrease below a body temperature threshold of 34.4 +/- 0.7 degrees C. EMG activity increased (P < 0.023) curvilinearly during body cooling; the main increase occurred between body temperatures of 38 and 33 degrees C (+142%, P < 0.001), and changes in EMG activity between 33 and 30 degrees C were not significant (+18%, P > 0.1). A marked increase in circulating levels of glucose (+312%, P < 0.001), glucagon (+76%, P < 0.05), adrenaline (+172%, P < 0.05) and noradrenaline (+113%, P < 0.05) occurred during body cooling. Insulin levels were not detectable at 2 h of life and increased during body cooling. During 2 h of rewarming at 24 degrees C, heat production and EMG activity remained elevated, changes in carbohydrate metabolism were not completely reversed and the final body temperature was only 35.6 +/- 0.9 degrees C. Rewarming of the piglets was faster at 34 degrees C. There was a net influx of heat into the animals and heat production and shivering activity decreased when body temperature reached 33.9 +/- 0.5 degrees C; the final body temperature was 37.5 +/- 0.2 degrees C. Circulating levels of lactate, glucagon and catecholamines returned to control levels. These results show that in conscious piglets exposed to a constant cold temperature there is an inverse relationship between EMG activity and body temperature during moderate hypothermia and that the thermoregulatory response and carbohydrate metabolism of the piglet are seriously impaired below a body temperature of 34 degrees C.

Energy metabolism in pregnant sows and newborn pigs.

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.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-.75.100 min-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.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.kg BW-.75.min-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.

Effect of fat content of colostrum on voluntary colostrum intake and fat utilization in newborn pigs.

The effects of colostral fat level on voluntary colostrum and ME intake were determined in 25 newborn pigs during the first postnatal day. Within a litter, five pigs were obtained before nursing and allotted on the basis of initial body weight (BW) at 2 h of age to one of the five treatments: killed or ad libitum bottle-fed sow colostrum containing 2.5, 5.0, 7.5, or 10.0% of total fat. A total of 24 feedings was provided at 60-min intervals, and pigs were killed 1 h after the final feeding. Total colostrum intake averaged 584.8 +/- 42 g (i.e., 436 g/kg of average BW) with the first two feedings accounting for 19.8% of the total consumption. Colostrum intake decreased linearly (P < .08) by 5.9 g/kg of average BW per 1% increase in the level of fat. However, GE and ME intake increased linearly (P < .01) by 7.65 and 4.09 kcal/kg average BW per 1.0 g/kg of average BW increase in fat intake, respectively. Adipose tissue lipoprotein lipase increased (P < .01) during the first postnatal day. Carcass fat deposition and fat oxidation increased linearly (P < .01) by .36 and .20 g/kg of average BW per 1.0 g/kg of average BW increase in fat intake, respectively. We suggest that increasing the fat content in colostrum has little effect on voluntary colostrum intake, and the practice may be an efficient method for improving the energy supply to newborn pigs.

Effects of the level of asphyxia during delivery on viability at birth and early postnatal vitality of newborn pigs.

Newborn pigs (n = 117) were used to provide information on the relationships of degree of asphyxia during delivery, viability at birth, and some striking aspects of postnatal vitality including survival, interval between birth and first udder contact and between birth and first suckling, rectal temperature at 24 h of life (RT24), and growth rate over the first 10 d of life. The degree of asphyxia at birth was estimated from cord blood pCO2, pH, and lactate levels. Onset of respiration, heart rate, skin color, and attempts to stand during the first minute after birth were used to estimate the viability score. Neonatal asphyxia, i.e., decreased blood pH and increased blood pCO2 and lactate, was associated with the production of unusually high levels of catecholamines. The degree of asphyxia increased with late position in the birth order (P < .01) and was higher in piglets born posteriorly (P < 0.5). Further, the average blood pCO2 within a litter increased (P < .05) with litter size. The was an inverse relationship between the degree of asphyxia and the viability score (P < .001). Highly viable piglets reached the udder more rapidly (P < .001) and had a higher RT24 (P < .001) than those of low viability. Plasma glucose concentrations increased with blood pCO2 and plasma epinephrine concentrations (P < .001). Neonatal asphyxia reduced postnatal vitality by delaying the first contact with the udder (P < .03) and was associated with a lower RT24 (P < .05), growth rate (P < .001), and survival over 10 d (P < 0.06). These variables, i.e., interval between birth and first udder contact, RT24, and growth rate, were correlated with birth weight (P < .001); RT24 was also shown to decrease (P < .001) with the time taken to reach the udder. Overall, results suggest that piglet suffering from asphyxia during delivery are less viable at birth and less prone to adapt to extrauterine life.

Metabolic changes associated with sustained 48-hr shivering thermogenesis in the newborn pig.

Metabolic changes associated with sustained 48-hr shivering thermogenesis were studied in piglets maintained at 34 (thermoneutrality) or 25 degrees C (cold) between 6 and 54 hr of life. Despite their high shivering activity and elevated heat production, cold-exposed piglets exhibited a slightly lower rectal temperature than thermoneutral animals (-1.1 degrees C; P < 0.01) at the end of the treatment. The enhancement of heat production and shivering activity were associated with a decrease in muscle glycogen (-47%; P < 0.05) and total lipid content (-23%; P < 0.05), a reduction of blood lactate levels (P < 0.05) and an enhancement of muscle cytochrome oxidase activity (+20%; P < 0.05) which suggests that muscle oxidative potential was increased by cold exposure. Potential for capturing lipids (lipoprotein lipase activity) was also higher in the red rhomboideus muscle (+71%; P < 0.01) and lower in adipose tissue (-58%; P < 0.01) of the cold-exposed piglets. Measurements performed at the mitochondrial level show no changes in rhomboideus muscle, but respiratory capacities (state IV and FCCP-stimulated respiration) and intermyofibrillar mitochondria oxidative and phosphorylative (creatine kinase activity) capacities were enhanced in longissimus dorsi muscle (P < 0.05). These changes may contribute to provide muscles with nonlimiting amount of readily oxidable substrates and ATP necessary for shivering thermogenesis. A rise in plasma norepinephrine levels was also observed during the second day of cold exposure (P < 0.05).