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Multiparity reveals the blunting effect of breastfeeding on physiological reactivity to psychological stress.

Rat studies show that hypothalamic-pituitary-adrenal (HPA) responsiveness to physical and emotional stressors is attenuated during lactation, although situations evoking pup endangerment can supersede this phenomenon. In the human population, blunted cortisol responses are seen in primiparous breastfeeding compared to bottlefeeding mothers following physical stress, but not after psychosocial stress. It is currently unknown whether stressor salience (child-related versus nonrelated stressor) has a differential effect on cortisol reactivity as a function of infant feeding choice and whether HPA responses to stress could be modified by parity. We investigated the impact of infant feeding type and maternal parity on salivary cortisol and alpha-amylase response to stress in 5-20-week postpartum mothers using exposure to the Trier Social Stress Test (TSST) and to an emotional film evoking threats to a child. Analyses show that alpha-amylase responses were similar in all groups and for both types of stress, suggesting that sympathetic reactivity was independent of infant feeding type and parity. By contrast, cortisol response was affected by these variables. In primiparous mothers, cortisol reactivity to psychological stressors did not vary as a function of infant feeding type while, among multiparous mothers, breastfeeding was associated with reduced responsiveness to the TSST and child-related stressor. We speculate that changes in neural mechanisms occurring as a result of pregnancy and lactation and that modulate the HPA axis in women might be exacerbated with multiple repeats of the pregnancy/lactation period. This would serve to 'desensitise' stress circuits and reduce the overall stress-induced cortisol secretion after multiple births.

Adaptation, Physiological↗

Cytotoxic antibodies in sera of Venezuelan multiparous women of Amerindian and mixed ethnic origin.

Sera from 464 multiparous women of mixed ethnic origin and 114 Amerindian mothers (Warao of Western Venezuela), were studied for lymphocytotoxicity using a panel of B and T lymphocytes isolated from 50 to 100 individuals from the same populations. Twenty-five and 9.65% of the sera, respectively, showed activity against at least 5% of the panel. Among the women of mixed ethnic origin 10% produced antibodies directed against one or more HLA Class I antigens while 2 sera contained monospecific anti-DR antibodies; among the Warao, only 2 sera recognized HLA antigens: a Bw51 and an undetermined Cw antigen which shows linkage disequilibrium with Bw16 in both populations.

Adult↗

Ovulation as determined by transrectal ultrasonography in multiparous sows: relationships with oestrous symptoms and hormonal profiles.

Twenty-four cross-bred multiparous sows in their second and fourth parities were studied during two consecutive oestruses after weaning. Careful oestrous control was done on the animals and ovulation was monitored by transrectal ultrasonography. Blood for analysis of LH and E2 contents was collected through an indwelling catheter. The sows were mated/inseminated once approximately 18 h before expected ovulation in their second oestrus. The interval between weaning and ovulation varied from 86 h-204 h (153 +/- 26). Onset of standing oestrus to ovulation was found to be longer in sows with long oestruses and ovulation occurred within a mean of 68% of the oestrous period. Duration of the first pro-oestrus was significantly shorter than the second pro-oestrus (40 h and 71 h, respectively). There was no significant difference within sows for the intervals from onset of oestrus to ovulation during the first and second oestrus after weaning (37 h and 39 h, respectively). The diameter of the largest follicles at onset of oestrus and at ovulation had very small variation between animals. The mean intervals from E2 peak to onset of oestrus and to ovulation were 1 h (range -10-(+)22 h) and 44 h (range 34-54 h) respectively, and from LH peak to onset of oestrus and to ovulation 12 h range -10-(+)32 h) and 35 h (range 27-48 h), respectively. The present study indicates that repeated ultrasonographic examination of ovaries during one oestrus can be used to predict the time of ovulation during the subsequent oestrus.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

Progress of first stage of labour for multiparous women: an observational study.

As there is no universal definition of 'normal' labour, diagnosing prolonged labour is inherently difficult. Simple charts (partograms) are used to aid this process; however, there are little empirical data on which to base such charts. Therefore, we monitored 403 multiparous women, in the first stage of labour with uncomplicated term pregnancies, in a midwife-led unit. They had vaginal examinations every 2 hours, and we modelled rates of cervical dilatation for all women, either to the end of the first stage of labour or to the point of transfer for intervention. Overall, the median rate of dilatation was 1.9 cm/hour and the 5th percentile was 0.5 cm/hour. There was a weak positive correlation between initial dilatation and rate of dilatation (r= 0.2). Individualised computer-based partograms incorporating some of the factors that affect progress might prove useful in the future.

Adult↗

Procurement and identification of HL-A lymphocytotoxic antibodies in sera of nonpregnant, multiparous blood donors.

An efficient procedure for large-scale screening of nonpregnant multiparous blood donor sera is described. Yield of useful HL-A reagents in this population compares favorably to yields obtained from screening pregnant women near term. The advantages of screening nonpregnant donors include stable antibody titers, ease of procurement, and the willingness of voluntary blood donors to return for plasmapheresis.

Blood Donors↗

Blastogenic response of peripheral blood lymphocytes from multiparous pregnant ewes.

The immunocompetence of pregnant multiparous ewes was investigated with respect to the blastogenic response of peripheral blood lymphocytes of (PBL) to three mitogens: PHA, Con A, and PWM. The profile of PBL responses shows 1) progressive suppression at 36 and 66 days of gestation, 2) enhanced response at 97 days of gestation, which approaches the mean values observed at the premating period, and 3) a redecline of the response at 137 days of gestation to depressed values lower than observed at 36 and 66 days of gestation. The results suggest that mitogen-treated lymphocytes were depressed and that the immunodepressive factor(s), which can influence lymphocytes at the systemic level, may be involved in the maintenance of the ovine fetal semiallograft.

Animals↗

Effect of a treatment with eprinomectin or trichlorfon on the yield and quality of milk produced by multiparous dairy cows.

The effects of a strategic antiparasitic treatment against Hypoderma species and other parasites on the milk yield, composition, and somatic cell counts of 742 multiparous dairy cattle were investigated on 79 farms in a Hypoderma species-endemic area in western Switzerland; 357 of the cows were treated with eprinomectin, 252 with trichlorfon, and 133 were left untreated. The treatments were given between October and early December 1998, on average 53 days before calving. Milk yield, fat, protein and somatic cell counts were measured once a month until the end of lactation. Eprinomectin and trichlorfon significantly increased milk yield during the first month after treatment compared with the control cows by 2.14 (P < 0.001) and 2.50 kg per day (P < 0.001), respectively. Initially, the difference between the eprinomectin- and trichlorfon-treated animals was not significant, but the effect of eprinomectin on milk yield was persistent, whereas the effect of trichlorfon decreased significantly by 0.12 kg per day per month (P < 0.05). The somatic cell counts increased significantly slower in the treated cows than in the control cows (P < 0.05). Milk composition was not affected by the treatments.

Animals↗

Identification of collagen-induced arthritis loci in aged multiparous female mice.

Collagen-induced arthritis in mice is one of the most commonly used autoimmune experimental models, with many similarities to rheumatoid arthritis. Since collagen-induced arthritis is a complex polygenic disease there is a need for identification of several major disease-controlling genes. Because rheumatoid arthritis particularly affects aged women, we have in the present study identified new genetic regions critical for collagen-induced arthritis by studying aged female mice of a cross between NFR/N and B10.Q (H-2q haplotype). The mice in the present study had different reproductive histories, which did not significantly affect the onset, incidence or severity of the disease. A total of 200 female mice were used in a total genome-wide screening with 125 microsatellite markers. We found one new significant quantitative trait locus affecting the arthritis incidence, severity and day of onset on chromosome 11 (denoted Cia40), which colocalizes with a locus controlling pregnancy failure. Furthermore, a quantitative trait locus of suggestive significance associated with the incidence, severity and day of onset was identified on chromosome 1. Finally, a suggestively significant quantitative trait locus associated with collagen type II antibody titers was identified on chromosome 13. This study indicates that several gene loci control arthritis in aged multiparous females, and that at least one of these loci coincides with pregnancy failure.

Age of Onset↗

Pervasive context-dependent effects in the genetic architecture of complex and quantitative traits revealed by a powerful multiparent mapping population in yeast.

The genetic dissection of complex traits remains a major challenge in basic and biomedical research, but is essential for understanding the molecular pathways that shape phenotypic variation and for developing predictive models of trait and disease susceptibility. Here, we leverage a novel multiparent mapping population of budding yeast, CYClones, comprising 9,344 haploid strains derived from eight genetically diverse founders (~270,000 SNVs,&#x2009;~&#x2009;1 per 44 bp, capturing 56% of common variants and 32% of all variants with a minor allele frequency greater than 0.005 in the global population), to identify quantitative trait loci (QTL) and systematically investigate the genetic architecture of growth rates across ten environmental conditions. In total, we identified 349 QTL (ranging from 18 to 49 QTL per growth condition) that explained between 60% and 100% of narrow sense heritability across traits. The high power and resolution of CYClones revealed that growth traits exhibited distinct, condition-specific genetic architectures with extensive allelic heterogeneity, where a QTL was the result of multiple tightly linked causal variants. We also observed pleiotropy among QTL with complex, trait-dependent allele effects that are also consistent with allelic heterogeneity. Genetic complexity varied widely, with some traits showing nearly Mendelian architectures, while others were highly polygenic. Introgressed loci played a prominent role in the landscape of growth rate QTL, including a QTL localized to a 2.4 kb interval in the PCA1 cadmium transporter that explains 72% of variation in cadmium resistance and is largely driven by an introgression, and a non-additive interaction between the GAL3 regulator and introgressed GAL1/7/10 alleles, extending a previously described three-locus GAL-pathway incompatibility to a four-locus interaction. In both cadmium and galactose conditions, we show that allelic variation at a small number of loci stratifies the population into regulatory or physiological subgroups, each with distinct genetic architectures, a specific manifestation of epistasis we term allele-dependent stratification. Collectively, our results provide novel insights into the genetics of growth rates in budding yeast, the architectural features of genetic complexity, and demonstrate that CYClones is a powerful platform for revealing the molecular basis of complex trait variation.

Quantitative Trait Loci↗

Indicated labor induction with vaginal prostaglandin E2 increases the risk of cesarean section even in multiparous women with no previous cesarean section.

AIMS: To evaluate the impact of induction of labor with vaginal tablets of prostaglandin E2 on the rate of cesarean section (CS), and to identify possible predictors of successful vaginal delivery. METHODS: 1541 consecutive women admitted for induction of labor with vaginal tablets of PGE2 were retrospectively compared with 574 consecutive women with spontaneous onset of labor. RESULTS: Maternal age, nulliparity, previous CS, gestational age, and birth weight were similar in the study and control groups. The CS rate was twofold higher in the study group (20.7% vs 10.6%). CS rates in the study and control groups were 26.9% and 12.8% for the nulliparous women, and 11.2% and 5.1% for the multiparous women with no previous CS. Neither group had major maternal or fetal complications. A logistic regression model and stepwise analysis showed that nulliparity, previous CS, maternal age, number of PGE2 applications, birth weight, and the induction of labor by itself were independent significant risk factors for increased CS rate. CONCLUSIONS: Induction of labor with vaginal PGE2 tablets results in a vaginal delivery rate of 79.3%, with apparently no serious maternal or fetal complications. Nulliparity, and previous CS are the most significant risk factors for increased CS rate. However, even after these risk factors are excluded and controlling for possible predictors for CS, PGE2 induction is independently associated with a twofold increase in CS rate, most often because of labor dystocia.

Administration, Intravaginal↗

Periovulatory profiles of oestradiol, LH and progesterone in relation to oestrus and embryo mortality in multiparous sows using transrectal ultrasonography to detect ovulation.

The timing of oestrus, the concentrations of oestradiol, LH and progesterone, and embryo survival on day 35 of pregnancy in 16 weaned multiparous sows were studied in relation to the moment of ovulation. Ovulation was detected using transrectal ultrasonography. The interval between weaning and ovulation varied between 126 and 214 h (156 +/- 29). The peak oestradiol concentration was 27 +/- 17 pg ml-7; sows with a shorter interval between weaning and ovulation had higher peaks of oestradiol (r = -0.54, P = 0.02). The interval between the peak oestradiol concentration and peak LH concentration was 11 +/- 4 h. The shape, width and height of the LH surge were variable, but did not influence the interval between the peak LH concentration and ovulation, which varied between 26 and 34 h (30 +/- 3). The interval between ovulation and the time when the progesterone concentration rose to more than 1.0 ng ml-1 above basal progesterone concentrations varied from 6 to 19 h (13 +/- 4). Ovulation took place at a more or less constant relative time of the oestrous period (after 72 +/- 8% of the duration of oestrus), irrespective of the duration of oestrus. The timing of the peak concentrations of oestradiol and LH and the rise in progesterone concentrations were closely related to the occurrence of ovulation but not to the onset of oestrus. Embryo survival on day 35 of pregnancy was related to the interval between the peak concentrations of oestradiol and LH (r = -0.68, P = 0.02); shorter intervals resulted in higher embryo survival.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

Effect of uterine manipulation 35 days after parturition on plasma concentrations of 13, 14-dihydro-15-keto prostaglandin F2 alpha in multiparous and primiparous Brahman cows.

Thirteen multiparous (M; 451 kg, 6.1 body condition score) and 11 primiparous (P) Brahman cows (408 kg, 6.3 body condition score) were assigned randomly within parity to receive either 2-min uterine manipulation (UM) per rectum 35 d after calving or no UM (C). This resulted in four groups: MUM (n = 8), MC (n = 5), PUM (n = 5) and PC (n = 6). All animals received a jugular cannula on d 34. Blood samples were collected at 10-min intervals from 30 min prior to UM until 120 min after UM and at 20-min intervals through 300 min after UM. Plasma was harvested immediately and stored at -20 degrees C until RIA for 13, 14-dihydro-15 keto prostaglandin F2 alpha (PGFM). Number of PGFM peaks in 330 min and amplitude of these peaks were similar (P greater than .10) in MC (2.0 peaks, 445.6 pg/ml) and PC (1.8 peaks, 446.9 pg/ml). Response to UM differed (P less than .02) by parity. The PGFM response of UM and C primiparous cows did not differ. Mean PGFM concentrations between 70 and 300 min after UM were greater (P less than .05) in MUM than in MC cows. Area of the PGFM curve did not differ (P greater than .10) in primiparous groups but was greater (P less than .01) in MUM than in MC cows. Uterine manipulation 35 d after parturition increased plasma PGFM in M but not in P cows.

Animals↗

Influence of prepartum body condition score change on reproduction in multiparous beef cows calving in moderate body condition.

Multiparous, spring-calving beef cows (n = 250) were used to determine whether large changes in body energy reserves during mid- to late gestation influenced subsequent reproductive performance of cows calving in moderate body condition. In three states, cows were blocked by BW and body condition score (BCS; 1 = emaciated to 9 = obese) then allotted to receive either a high or low plane of nutrition from late summer to early winter over a 3-yr period. This generated an array of BCS by the beginning of the last trimester of pregnancy when cows were grouped by BCS as follows: Group 1, BCS < or = 4; Group 2, BCS of 5 or 6; and Group 3, BCS > or = 7. Each group was managed so that individual cows would calve with a BCS of 5 to 6. At the time of group assignment, mean BW and BCS differed (P < .01) among groups and were 480 kg and 3.6, 541 kg and 5.5, and 594 kg and 7.1 for Groups 1 to 3, respectively. Within 28 d before calving, BW and BCS were similar (P > .20) among groups averaging 555 kg and 5.1. Prepartum BCS changes averaged 1.4, -.4, and -2.0 units for Groups 1 to 3, respectively (P < .01). Cows were managed as a single group after calving in each state. Location effect was significant for the prepartum and postpartum BW and BCS changes but not for postpartum reproductive performance. Significant location x BCS group interactions were found for the 90-d prepartum BW, BCS at calving, and prepartum changes in BW, but were caused by differences in magnitude among locations. The percentage of cows with luteal activity at the start of a subsequent breeding season was not affected (P > .20) by either location or BCS group, and averaged 66%. Mean pregnancy rates at 20, 40, and 60 d of a subsequent breeding season were 55, 76, and 89% for Group 1; 51, 67, and 82% for Group 2; and 64, 79, and 89% for Group 3 (P > .30). Mean days to conception were 89, 87, and 85 for Groups 1 to 3, respectively (P = .70). Neither calf birth weight (x = 38.6 kg) nor adjusted 205-d weight (x = 223.6 kg) were affected by prepartum BW and BCS changes. We conclude that reproductive performance of cows calving in moderate body condition is not influenced by large changes in body energy reserves during the last trimester of pregnancy.

Analysis of Variance↗

Influence of high ambient temperatures on performance of multiparous lactating sows.

Multiparous Large White sows (n = 63) were used to investigate the effects of five ambient temperatures (18, 22, 25, 27, and 29 degrees C) and two dietary protein contents on their lactation performance. At each temperature treatment, ambient temperature was maintained constant over the 21-d lactation period. Dietary protein content was either 14 or 17% with essential amino acids levels calculated not to be limiting. The animals had ad libitum access to feed between the seventh and the 19th day of lactation. Diet composition did not influence lactation performance. Over the 21-d lactation, feed intake decreased from 5.67 to 3.08 kg/d between 18 and 29 degrees C. Between d 7 and 19, the corresponding values were 7.16 and 3.48 kg/d, respectively. This decrease was curvilinear; an equation to predict voluntary feed intake (VFI) from temperature (T, degrees C) and body weight (BW, kg) is proposed: VFI = -49,052 + 1,213 T - 31.5 T2 + 330 BW - .61 BW2 (residual standard deviation: 1,018). Skin temperature increased regularly with increased ambient temperature (34.6 to 37.4 degrees C between 18 and 29 degrees C), whereas udder temperature reached a plateau at 25 degrees C (38.3 degrees C). The gradient of temperature between skin and rectum was minimal (2 degrees C ) at 27 degrees C and remained constant at 29 degrees C. This constancy coincides with the marked reduction of feed intake. The respiratory rate increased from 26 to 124 breaths/min between 18 and 29 degrees C, and this indicates that the evaporative critical temperature was below 22 degrees C. The BW loss increased from 23 to 35 kg between 18 and 29 degrees C, but its estimated chemical composition remained constant. Pig growth rate was almost constant between 18 and 25 degrees C (241 g/d) and was reduced above 25 degrees C (212 and 189 g/d at 27 and 29 degrees C, respectively). In conclusion, temperatures above 25 degrees C seem to be critical for lactating sows in order to maintain their performance.

Animal Feed↗

Effects of exposure to high ambient temperature and dietary protein level on performance of multiparous lactating sows.

Fifty-nine multiparous Large White x Landrace sows were used to determine the effects of high ambient temperature and level of dietary heat increment on lactation and reproductive performance. During a 28-d lactation and the 14-d postweaning period, ambient temperature was maintained constant at 20 or 29 degrees C. Experimental diets fed during lactation were a control diet (NP; 17.6% crude protein) and two low-protein diets obtained by reduction of CP level (LP; 14.2% CP) and both reduction of CP and addition of 4% fat (LPF; 15.2% CP); the NE:ME ratio was 74.3, 75.6, and 75.8% for NP, LP, and LPF diets, respectively. All diets provided 0.82 g of digestible lysine/MJ of NE, and ratios between essential amino acids and lysine were above recommendations. During the ad libitum period (i.e., between d 7 and 27 of lactation), ADFI and NE intake decreased, respectively, from 7.63 to 4.22 kg and 82.0 to 43.3 MJ of NE when the temperature increased from 20 to 29 degrees C. Exposure to 29 degrees C reduced litter BW gain (2,152 vs 2,914 g/d) and increased lactation BW loss (34 vs 16 kg) but increased postweaning BW gain (2 vs - 4 kg). Expressed per kilogram of feed intake, water intake increased from 4.0 to 7.5 L between 20 and 29 degrees C. Compared with the NP diet, low-CP diets (LP or LPF) maintained performance and reduced total N excretion (-22.5%) in lactating sows at thermoneutrality and attenuated the negative effects of high temperature on NE intake and BW loss (40.9 vs 47.9 MJ of NE/d and 41 vs 30 kg for NP and LP + LPF diets, respectively). Temperature and diet composition did not affect the reproductive performances, and the mean weaning-to-estrus interval was 4.9 d. The respiratory rate and skin, udder, and rectal temperatures increased markedly at 29 degrees C (105 vs 33 breaths per min and 37.8 vs 36.1 degrees C, 38.9 vs 38.2 degrees C, and 39.5 vs 38.8 degrees C, respectively) without any effect of diet. In conclusion, low heat increment diets (i.e., with reduced CP/NE ratio) did not affect lactation performance of sows at thermoneutrality and attenuated the effects of high ambient temperature on energy intake and BW loss. At any ambient temperature, N excretion can be markedly reduced.

Animal Feed↗

Metabolic characteristics of multiparous Angus and Brahman cows grazing in the Chihuahuan Desert.

Understanding metabolic differences between breeds of cattle is important when selecting for production in semiarid environments. Spring-calving multiparous Angus and Brahman cows (n = 8/breed) grazing in the Chihuahuan Desert were used to evaluate metabolic hormone status in February (i.e., 3rd trimester of pregnancy), May (i.e., early lactation), and September (i.e., late lactation) 2000. Crude protein in ruminal digesta collected from grazing companion ruminally cannulated cows during these months was 5.6, 6.0, and 10.3%, respectively. Angus cows were heavier (P < 0.01) than Brahman cows across months. Body condition scores among breed groups were 4.4, 3.6, and 4.6 in February, May, and September with Brahman cows tending (P < 0.10) to have greater body condition than Angus cows in May. Brahman cows tended to have greater fecal output per 100 kg BW than Angus cows in February (0.9 > 0.7 +/- 0.1, P < 0.10). Brahman cows had greater serum concentrations of leptin than Angus cows in September (1.8 > 0.70 +/- 0.1 ng/mL; P < 0.05), and serum concentrations of insulin were greater (P < 0.01) in Brahman than Angus cows throughout the study. Brahman cows also had greater (P < 0.01) serum concentrations of glucose during February and May than Angus cows. Serum concentrations of triiodothyronine were greatest (P < 0.01) during September and lowest during February and May in both breed groups and were greater (P < 0.01) in Brahman than in Angus cows in February, May, and September. Pregnancy rate and 205-d adjusted weaning weights were similar (P > or = 0.46) among breed groups. Results suggest that Brahman and Angus cows are sensitive to the seasonal dynamics of forage quality in the Chihuahuan Desert. Brahman cattle appear to have greater concentrations of metabolic hormones and metabolites than Angus cows in this environment, but Angus cows experience greater fluctuations in BW.

Animal Feed↗

Effects of dietary fiber on performance of multiparous lactating sows in a tropical climate.

Sixty-two multiparous Large White sows were used to determine the effect of dietary fiber level on lactation performance according to season under conditions of a humid tropical climate. This experiment was conducted in Guadeloupe (West French Indies, lat 16 degrees N, long 61 degrees W) between October 1999 and January 2001. Two seasons were distinguished a posteriori from climatic measurements parameters continuously recorded in the farrowing room. During the warm season, ambient temperature and relative humidity averaged 25 degrees C and 86.8%, respectively. The corresponding values for the hot season were 27.5 degrees C and 83.5%. Experimental diets fed during lactation were a control diet (C; 14% neutral detergent fiber) and a high-fiber diet (HF; 20% neutral detergent fiber) obtained by substitution of wheat middlings by wheat bran. The two diets were formulated to provide the same ratios between essential amino acids and lysine and between lysine and net energy. No interaction between season and diet composition was found for all criteria studied. Over the 28-d lactation, average daily feed intake (ADFI) was lower and body weight loss was higher (P < 0.001) during the hot season compared to the warm season (3,447 vs 4,907 g/d and 33 vs 17 kg, respectively). The number of stillborn piglets was higher (P < 0.05) during the hot season than during the warm season (2.0 vs 1.1 piglets, respectively). Litter growth rate and mean BW of piglets at weaning were reduced (P < 0.01) during the hot season vs the warm season (2.1 vs 2.3 kg/d and 7.7 vs 8.3 kg, respectively). The ADFI was similar for both diets and digestible energy (DE) intake tended to be lower (P = 0.06) with the HF diet (54.9 vs 59.3 MJ of DE/d for C sows) in relation with its lower DE concentration. The body weight loss was greater (P < 0.01) for HF sows than for C sows (30 vs 21 kg). Compared with the C diet, the HF diet increased (P < 0.05) litter growth rate and piglet body weight at weaning (2.3 vs 2.1 kg/d and 8.3 vs 7.7 kg/d for HF vs C, respectively). Season and diet composition did not affect the weaning-to-estrus interval. In conclusion, the hot season in humid tropical climates, which combines high levels of temperature and humidity, has a major negative effect on the performance of lactating sows.

Animal Feed↗

Effects of season and breed on the feeding behavior of multiparous lactating sows in a tropical humid climate.

The effects of breed and season on performance and feeding behavior were studied during 76 lactations in multiparous Large White (LW; n = 17) and Creole (CR; n = 23) sows reared in a humid tropical climate. The experiment was conducted in Guadeloupe (French West Indies, latitude 16 degrees N, longitude 61 degrees W) between May 2002 and July 2004. Average daily ambient temperature was greater during the hot season than during the warm season (26.0 vs. 23.8 degrees C), but relative humidity was similar in both seasons (85% on average). The daily fluctuations of ambient temperature and relative humidity were similar for both seasons. At farrowing, BW was lower (187 vs. 265 kg) and backfat thickness was greater (40 vs. 22 mm) in CR than in LW sows (P < 0.01). Sows were offered feed ad libitum between the fifth and the 26th day of lactation. There was a breed x season interaction (P < 0.05) for ADFI. During the hot season the reduction of ADFI was more pronounced in LW than in CR sows (-1,100 vs. -300 g/d). Irrespective of breed and season, the daily number of meals was 9.0. The meal size and the rate of feed intake were greater in LW than in CR sows, respectively (555 g and 153 g/min vs. 390 g and 83 g/min; P < 0.01). The diurnal proportion of ADFI was greater in CR than in LW sows (0.60 vs. 0.41; P < 0.01). The reduction in ADFI in LW sows during the hot season was mainly related to a reduction in feed intake during the day rather than during the night (-1.3 vs. -0.2 kg; P < 0.01). Duration of standing was not affected by breed or season, and it averaged 120 min/day. This study confirms the negative effect of the hot season on feeding behavior of lactating sows. It also suggests a better acclimation to daily high temperatures and a greater heat tolerance in CR compared with LW sows, at least for eating behavior.

Animals↗