Influence of pregnancy, lactation and environment on some clinical chemical reference values in Danish landrace dairy goats (Capra hircus) of different parity--I. Electrolytes and enzymes.

1. Plasma calcium, magnesium, inorganic phosphorus, sodium and potassium concentrations, alanine aminotransferase, aspartate aminotransferase, alkaline phosphatase and creatine kinase activities were determined in young and adult non-pregnant non-lactating, early and late non-lactating pregnant and early, mid- and late non-pregnant lactating Danish landrace goats in five herds. The purpose was to determine the influence of pregnancy and lactation on the levels of these parameters and the effect of age and parity on the changes. 2. Calcium, phosphorus, alanine aminotransferase, alkaline phosphatase and aspartate aminotransferase decreased in late gestation. Magnesium and creatine kinase decreased in early lactating goats but increased in subsequent lactation periods. Sodium and potassium fluctuated little during pregnancy and lactation. Calcium, magnesium and potassium profiles were inversely, while phosphorus was directly, proportional to parity. 3. There were significant differences in most ions and enzymes between goats of different herds (within the same physiological state). 4. The transferases and creatine kinase were higher in young goats than in old ones, while alkaline phosphatase was unpredictably high or low in individual goats. 5. Alterations in the level of plasma electrolytes and enzyme activities occur due to pregnancy and lactation and the degree depends on age and parity, influenced also by environment.     

Influence of pregnancy, lactation and environment on haematological profiles in Danish landrace dairy goats (Capra hircus) of different parity.

1. Haematological analysis was performed in young and adult non-pregnant, non-lactating, early and late pregnant, early mid- and late lactating Danish landrace goats from five herds. The purpose was to determine whether their levels are significantly different in these states and the effect of age and parity on the changes. 2. The haematocrit, haemoglobin concentration, number of erythrocytes and leukocytes were higher in 8-12 month old non-pregnant and 1-2 year old pregnant goats than in adult pregnant and lactating goats of over 2 years of age. Haematocrit, haemoglobin concentration and the number of erythrocytes decreased in late pregnancy and early lactation. 3. At the same time mean corpuscular volume, mean corpuscular haemoglobin and mean corpuscular haemoglobin concentration slightly increased. 4. The changes were directly proportional to parity, more in pluriparous than in primiparous goats. 5. After parturition the former group of parameters increased and the latter decreased. 6. There was an increase in the number of total leukocytes close to and after parturition due to neutrophils and lymphocytes and it was more pronounced in the first lactation than in pluriparous goats. 7. There were significant differences in many parameters between goats from different herds (within similar physiological states).     

Circadian variations of plasma renin activity (PRA), aldosterone and electrolyte concentrations in plasma in pregnant and non-pregnant goats

The aim of this study was to estimate and analyse circadian variations of the renin-angiotensin-aldosterone system (RAA) activity in blood of goats and the influence of late pregnancy on the circadian variations of RAA system. The study was carried out on a group of 17 non-pregnant and 9 pregnant goats. The animals were kept in uniform environmental conditions, (9 h light/15 h darkness). Blood samples were collected seven times over a period of 24 h, every 4 h. Plasma renin activity (PRA), plasma aldosterone (PA), sodium, potassium and chloride concentrations were determined. PRA and PA of both groups changed during 24 h, with the highest values in the dark phase and with higher RAA system activity (especially during the night) in the pregnant goats. In the non-pregnant goats, no circadian changes in PRA and PA were observed. The circadian changes in PRA and PA found in pregnant goats had acrophases at 06:27 h and 01:13 h, respectively. Plasma electrolyte concentrations in both groups of goats also changed during 24 h. These results suggest that circadian changes of potassium concentration in plasma of goats during late pregnancy may be one of the main factors affecting the RAA system.     

Changes in some blood constituents of Barki ewes during pregnancy and lactation under semi arid conditions

A study based on 12 pregnant and six dry Barki ewes was carried out to examine the changes in blood constituents during pregnancy and lactation periods. The blood parameters were blood hemoglobin, packed cell volume percent (PCV%), mean corpuscular hemoglobin concentration (MCHC), glucose, aspartate aminotransaminase (AST or GOT), alanine aminotransaminase (ALT or GPT), total plasma protein, albumin, globulin, albumin to globulin ratio (A/G), urea and creatinine. During pregnancy all these parameters started to increase significantly, but in different stages, reaching maximum values at parturition. In contrast, dry ewes showed almost stable values during the experimental period. From 10th week to parturition, PCV% and MCHC increased (P<0.01) in pregnant ewes, which resulted in increased (P<0.01) blood hemoglobin. Blood glucose increased from the 4th week of pregnancy to reach its maximum at parturition (60.15–90.08 mg/dl). The two transaminases increased significantly from the 2nd week (52.23–65.02 IU for AST and 8.02–15.12 IU for ALT). Plasma protein with its two components, albumin and globulin, increased significantly at the 6th week, but dropped throughout the 16–18th week of pregnancy. Urea and creatinine began to increase significantly after 10–12 weeks of pregnancy (from 54.73 to 72.11 mg/dl for urea and from 0.882 to 2.475 mg/dl for creatinine). During the first month of lactation, PCV decreased sharply in lactating ewes and was significantly lower than in dry ewes at the 3rd week of lactation (24.25 versus 27.17%), which resulted in a drop in blood hemoglobin at the 4th week (68.42 versus 74.00 g/l). However, lactating ewes maintained significantly higher values of MCHC (30.01–31.19% for lactating versus 29.87–27.48% for dry). In lactating ewes, levels of glucose, ALT, urea and creatinine returned to levels comparable to those in dry ewes. The same occurred with total plasma proteins, mainly due to a sharp decrease in globulin, while albumin remained higher than in dry ewes with a slow decline, which resulted in higher values of A/G ratio during lactation. Aspartate aminotransferase remained higher than in dry ewes.     

Water movements after an intraruminal water load in pregnant and lactating Sardi sheep

The effects of an intraruminal load of 3 litres of water on body water movements was compared in Sardi sheep during the last month of pregnancy, lactation and a non-pregnant, non-lactating control period. Before the water load, rumen fluid volume, estimated by polyethylene glycol was similar in pregnant, compared to control, animals and 27% higher in lactating sheep. After the water load, rumen volume returned to pre-hydration level in 1 h during pregnancy, after 3 h during lactation and in the control period. Rumen osmolality decreased by 40% and remained at this low level for 3 h after the water load in all physiological periods. When the water load was tritiated water (TOH), the rate of TOH transfer into plasma was faster during the last month of pregnancy than during the control period. Plasma osmolality and proteins decreased in response to the water load. No differences in these responses were observed between pregnancy, lactation and the control period. Water diuresis began in the first 30 min following the water load in pregnant ewes and in the second 30 min in lactating and control ewes. The diuresis was also more pronounced in pregnant, than in non-pregnant, states. These results indicate that water is more rapidly absorbed from the gastrointestinal tract in pregnant, rather than in non-pregnant, sheep. This may partly explain the increased water turnover seen during pregnancy.     

In-vivo studies of mammary development in the goat using magnetic resonance imaging (MRI)

Mammary development and regression were measured in goats in vivo using magnetic resonance imaging (MRI). Measurements were made during the first and second cycles of pregnancy, lactation and involution. In primiparous goats, and exponential pattern of growth was evident during gestation and for the first 2 weeks of lactation. Parenchyma volume correlated significantly with milk yield across goats during early lactation, and across stage of lactation within goats. Milking was discontinued in Week 26 of the first lactation. Involution was characterized by an initial accumulation of fluid (over 2 days) followed by reabsorption; parenchyma volume did not decrease significantly until the 3rd week of involution, which was also the time at which these goats were mated to start their second gestation. Their udders still contained significant quantities of fluid (40-60% of the gross volume), but parenchyma volume was also greater (by 4.7-fold) than in goats beginning their first gestation. By Week 15 of gestation there was no longer a parity difference in parenchyma; the udders of first-gestation goats had grown significantly, but those of second-gestation goats had not. Conversely, between gestation Week 15 and lactation Week 2 mammary growth was significantly more rapid in the second cycle, such that the udder was larger at the start of the second lactation.     

Comparison of reproductive performance by artificial insemination versus natural service sires in California dairies

This study compared the calving to conception intervals for cows in AI pens with cows exposed to natural service sires, controlling for milk production, mastitis occurrence, parity and calving month effects. Records from 10 western United States dairy herds (mean herd size = 2058 cows) were evaluated retrospectively over an 18-month period. Eight bull breeding analysis cohorts were created (the first cohort 0-50 days in milk and the remaining cohorts at 25 days in milk intervals through 226 days). The cohorts contained non-pregnant cows that were first moved into bullpens during the described cohort period. Equal numbers of non-pregnant cows only exposed to AI during the cohort period were randomly selected from the pool of eligible non-pregnant cows. An AI cow was used only once in the data analysis, but was included in a bull breeding cohort at a later date if she remained non-pregnant and was transferred to a bullpen. Univariate and multivariate survival analysis was used to compare the calving to conception intervals. Cows in AI groups had higher hazard rates for pregnancy across all cohorts. Parity and milk production were significantly associated with risk for pregnancy. In herds that practice a mixture of AI and bull breeding, overall herd reproductive performance might be improved by allowing cows more opportunities at AI prior to moving them into clean-up bullpens.     

Regulation of ghrelin secretion during pregnancy and lactation in the rat: possible involvement of hypothalamus

We investigated the plasma concentration of ghrelin peptide during pregnancy and lactation in rats. Plasma ghrelin levels on days 10 and 15 of pregnancy were significantly lower than those of the non-pregnant rats. Thereafter, the plasma ghrelin levels on day 20 of pregnancy sharply increased to levels comparable with those in non-pregnant rats. Ghrelin peptide concentrations in the stomach did not change significantly during pregnancy. In the hypothalamus, ghrelin mRNA levels were significantly lower on day 15 of pregnancy than in the non-pregnant rats. Also, plasma ghrelin levels were significantly lower in lactating dams than non-lactating controls on days 3 and 8 of lactation. We examined the possible involvement of prolactin and oxytocin in the regulation of plasma ghrelin concentrations during lactation. Although plasma prolactin levels were decreased by the administration of bromocriptine, plasma ghrelin levels did not differ significantly between vehicle- and drug-treated lactating rats. Administration of haloperidol produced a marked increase in plasma prolactin levels as compared with the non-lactating controls. However, plasma ghrelin levels were not significantly different between vehicle- and drug-treated rats. Administration of an oxytocin antagonist into the lateral ventricle significantly inhibited the increase in the plasma oxytocin level induced by acute suckling. However, plasma ghrelin levels did not significantly between the groups. These observations indicated that the decrease in serum ghrelin is caused by a loss of the contribution of hypothalamic ghrelin. Furthermore, the present results suggested that the suckling stimulus itself, but the release of prolactin or oxytocin, is the factor most likely to be responsible for the suppression of ghrelin secretion during lactation.     

Selection for nutrients by pregnant goats on a microphyll desert scrub

The behavioral consequences of pregnancy in goats were studied to test the hypothesis that pregnant females on rangeland select a diet richer in nutrients once the demands of gestation increase, and that nutrient content in goat diets changes with the grazing season. A total of 12 mature mixed breed goats either pregnant (n = 6) or non-pregnant (n = 6) were used during the dry period (February to May). Dietary samples obtained from the oral cavity of grazing goats (restrained with a short light rope permanently tightened around their neck) were used for chemical analyses. Across months, pregnant goats selected diets higher (P < 0.01) in crude protein (CP) than non-pregnant goats; this nutrient did not meet the requirements of late gestating goats. Pregnant goats made use of less (P < 0.01) fibrous feeds than non-pregnant goats. In order to cope with changing nutrient demands for pregnancy, goats adjusted their diet by increasing the selection of plants with 32% higher calcium content compared to forages selected by non-pregnant goats. The physiological state of goats did not alter the levels of phosphorus (P), magnesium (Mg) and sodium (Na) in their diets; these minerals were adequate to meet the demands of pregnancy. There were no effects of physiological state on concentrations of copper (Cu), zinc (Zn), manganese (Mn) and iron (Fe) in the goat diets during the dry season, with levels adequate for sustainability of pregnancy. Pregnant goats did not seek forages lower in tannins, alkaloids, saponins and terpenes. It was concluded that to cope with increasing pregnancy costs, goats adjusted their diets increasing selection of forages or plant parts with high nutritional value to maximize their net nutrient budget.     

Urinary selenium and iodine during pregnancy and lactation

The New Zealand environment is low in selenium and iodine, and is therefore ideally suited for the study of these anionic trace elements. The aim of this study was to determine urinary excretion of selenium and iodine during pregnancy and postpartum as part of an investigation of the influence of pregnancy and lactation on selenium metabolism in women of low selenium status. In a double-blind placebo-controlled study, 35 women in the earliest stages of pregnancy and 17 non-pregnant women were recruited in Dunedin, New Zealand. Eighteen pregnant women received 50 μg selenium as L-selenomethionine, while the others received a placebo daily during pregnancy and 12 months postpartum. The non-pregnant women received the supplement, serving as a positive control. Blood samples and twenty-four hour urine samples were collected monthly during pregnancy and at 3, 6, and 12 months postpartum for analysis of selenium and iodine. Selenium content in plasma and urinary excretion of selenium fell during pregnancy; however, total excretion of selenium was greater during pregnancy than postpartum. Urinary iodine excretion was much lower than reported previously in New Zealand. Due to large intra- and inter-subject variability, no trends in iodide excretion were observed. Factors which influence urinary excretion of selenium include dietary intake, but more closely, plasma concentrations of selenium (which is probably related to total selenium pool), creatinine excretion and therefore lean body mass, and glomerular filtration rate. The exact mechanism and sequence of events remains unclear and future studies incorporating new speciation techniques are necessary.     

Cumulative Risk of Bovine Mastitis Treatments in Denmark,Finland, Norway and Sweden

Data from the national dairy cow recording systems during 1997 were used to calculate lactation-specific cumulative risk of mastitis treatments and cumulative risk of removal from the herds in Denmark, Finland Norway and Sweden. Sweden had the lowest risk of recorded mastitis treatments during 305 days of lactation and Norway had the highest risk. The incidence risk of recorded mastitis treatments during 305 days of lactation in Denmark, Finland, Norway and Sweden was 0.177, 0.139, 0.215 and 0.127 for first parity cows and 0.228, 0.215, 0.358 and 0.204 for parities higher than three, respectively. The risk of a first parity cow being treated for mastitis was almost 3 times higher at calving in Norway than in Sweden. The period with the highest risk for mastitis treatments was from 2 days before calving until 14 days after calving and the highest risk for removal was from calving to 10 days after calving in all countries.The study clearly demonstrated differences in bovine mastitis treatment patterns among the Nordic countries. The most important findings were the differences in treatment risks during different lactations within each country, as well as differences in strategies with respect to the time during lactation mastitis was treated.     

Influence of oxidative stress and metabolic adaptation on PON1 activity and MDA level in transition dairy cows

Serum PON1 is a HDL-associated enzyme that protects lipoproteins, both LDL and HDL, against oxidation and it is considered as an antioxidative/anti-inflammatory component of HDL. Dairy cows are highly susceptible to oxidative stress which commonly occurs in late pregnancy and early lactation. During the transition period, increased production of reactive oxygen species is associated to processes of metabolic adaptation to a low-energy balance. We investigated serum paraoxonase-1 (PON1) activity and malondialdehyde (MDA) concentration to assess the antioxidative/prooxidative status during pregnancy and the postpartum period. In order to evaluate metabolic homeostasis, common metabolic parameters (glucose, triglyceride, total cholesterol, HDL-C and albumin concentrations) were determined as well. A significantly lower PON1 activity was found in late pregnancy and early postpartum (P<0.05) compared to the first and the second trimester of pregnancy and the mid-lactation. MDA level was significantly higher (P<0.05) in the dry period compared to pregnant lactating and postpartum cows. Serum glucose concentration (P<0.001) was lower in the early and late puerperium indicating low-energy balance in the early lactation. Serum triglyceride and albumin concentrations were lower in late puerperium (P<0.001), while total cholesterol and HDL-C were lower during the dry period (P<0.05) as well as in early postpartum (P<0.001). Significant correlations of PON1 activity with glucose (P<0.05), albumin (P<0.05), total cholesterol (P<0.001) and HDL-C (P<0.001) were also found. The observed lower serum PON1 activity and higher MDA level in late pregnancy and early postpartum could indicate a prooxidants/antioxidants imbalance influenced by reproductive stress and metabolic adaptation in the transition period of dairy cows.     

Biochemistry and haematology values for the baboon (Papio hamadryas): the effects of sex, growth, development and age.

A retrospective study evaluated the influence of sex and age on plasma biochemistry and haematology parameters in a captive-bred colony of baboons. Over 1,140 ETDA and heparin blood samples were obtained from 160 clinically normal baboons between the ages of 11 months and 11 years. Data for these blood tests were analysed for the effects of sex, age and sex age interactions. Sex, age and sex age interactions were detected for many plasma biochemistry and haematological parameters. The reference range values for platelets, white-blood cells and mean corpuscular volume and plasma chloride, glucose, total protein and iron were higher (P < 0.01) and red blood cell, plasma sodium, potassium, total CO2, creatinine, urea, total bilirubin, albumin, alkaline phosphate, gamma glutamyl transpeptidase and phosphate were lower (P < 0.01) in the female compared to the male population. Sex age interactions (P < 0.05) were seen with haemoglobin, white blood cells, haematocrit, mean corpuscular volume, sodium, creatinine, urea, calcium, phosphate, total bilirubin, total protein alkaline phosphatase, the liver enzymes and triglycerides. Plasma alkaline phosphatase was highest ( > 800 micro/l) in young juveniles of both sexes; creatinine was higher in older ( > 4 years) compared to younger baboons of the same sex (P < 0.05). Plasma cholesterol and triglycerides were greater (P < 0.01) in young baboons compared to older animals.     

Lipogenesis in interscapular brown adipose tissue of virgin, pregnant and lactating rats. The effects of intragastric feeding.

Lipogenesis in brown adipose tissue of virgin rats increased 8--10-fold after intragastric feeding with glucose or medium-chain triacylglycerol, and this increase was prevented by short-term insulin deficiency. Brown adipose tissue increased in weight during pregnancy, regressed during lactation and hypertrophied again on weaning; the rate of lipogenesis paralleled these changes. Glucose did not increase brown-adipose-tissue lipogenesis at mid-lactation.     

Effects of dietary energy intake during gestation and lactation on milk yield and composition of first, second and fourth parity sows

In order to determine the effects of a varied level of dietary energy intake during pregnancy and lactation on milk yield and composition, first, second and fourth parity sows (Large White x German Landrace) were provided with energy at a level of either: (i) 100% of ME requirement (MEreq) during pregnancy and lactation, (ii) 120% MEreq during pregnancy and 80% during lactation, and (iii) 80% MEreq during pregnancy and 120% during lactation. In spite of equal target levels feed analysis revealed that gestating first parity sows with 120/80 treatment combination and lactating sows of 80/120 treatment combination received 25, and 11-17% more digestible N than in the respective 100/100 treatment combination. Irrespective of this 120/80 sows responded with the highest milk DM, fat, and energy contents, and the lowest lactose concentrations whereas protein levels where not affected, irrespective of parity (p < 0.05). Milk yield of sows in 1st and 4th lactation was 85 and 106% of that in 2nd lactation, respectively. Average milk composition was 18.1% DM, 4.9% protein, 6.8% fat, 5.6% lactose, and 0.8% ash. Milk composition changes ceased at day 7 of lactation with a reduction of milk GE and protein, and an increase of lactose content. Concentrations of threonine, arginine, valine, leucine, tyrosine, phenylalanine, cystine, and tryptophan, as well as stearic, oleic, and linoleic acid were higher in colostrum than in milk at later lactation stages. In contrast, laurine, myristic, palmitic, and palmitoleic acids were lower concentrated in colostrum. In conclusion, these results illustrate the importance of body reserve mobilization for milk production in sows and indicate that low energy supply during gestation cannot be compensated by higher energy supply during lactation.     

Impact of indoor feeding at late lactation stage on body reserves recovery and reproductive performances of Baladi dairy goats fed on pastoral system

Adaptive capacities of Baladi goats facing situations of food restrictions and re-feeding during lactation have been studied. Three diets were tested: mountain natural rangelands during early lactation, agricultural pastures during mid-lactation and indoor stall feeding during late lactation. Body weight (BW), body condition (BCS) and plasma metabolites (NEFA) as well as milk production (milk yield, milk fat and milk protein contents) were measured in the different feeding situations. Effect of late lactation re-feeding on reproduction was assessed through kids’ birth weight and weight gain from day 0 till day 60 of age. Results showed that on rangelands, goats’ body condition degraded, with initially fat goats loosing more weight and being subject to a greater reserves mobilization than lean ones. These expressed an adaptive behaviour through increasing their daily feed intake and by an intense body reserves replenishment following their transfer to the agricultural pastures and indoor feeding. In late lactation, even goats kept on agricultural pastures showed a similar reconstitution, showing the high priority of body reserves replenishment during late lactation whatever the feeding level. The milk rebounds observed showed a good reactivity from the Baladi goat in response to a feed improvement either on agricultural pasture or indoor. At the end of lactation the milk yield decreased in all feeding situations proving the priority given by the Baladi goats to the body reserves replenishment over the milk production in order to ensure the next cycle. However, even if there was no difference in kids’ birth weights, kids from stall-fed dams had higher weight gains between 0 and 60 days of age when compared to those from underfed ones.     

Elevated leptin concentrations in pregnancy and lactation: possible role as a modulator of substrate utilization.

Energy needs are increased during pregnancy and lactation. These increased energy needs may be met through partitioning of nutrients for energy utilization which is under hormonal control. The objective of the present studies was to determine if changes in plasma leptin occurred during pregnancy and lactation and if the changes were related to prolactin. Plasma leptin and prolactin were measured longitudinally in 9 women through pregnancy and lactation. In a second study, leptin and prolactin were measured 4 days and 28 days postpartum in 21 lactating women. Mean plasma leptin during the three trimesters of pregnancy was significantly higher (29.3+/-2.8 ng/ml) when compared to mean leptin during the three time periods of lactation (19.3+/-3.2 ng/ml) and control groups (9.8+/-1.4 ng/ml). Plasma leptin was elevated early in pregnancy and remained elevated throughout pregnancy. In the second study, the mean plasma leptin in the lactating women was significantly higher 4 days postpartum (17.3+/-3.7 ng/ml) and 28 days postpartum (19.2+/-3.9 ng/ml) when compared to controls (11.6+/-1.2 ng/ml). Prolactin in the control subjects (24+/-4 ng/ml) was significantly lower than in the pregnant (202+/-16 ng/ml) and lactating (108+/-26 ng/ml) groups. Similar observations were made in the second study (controls 20+/-2 ng/ml; lactation 28 days 159+/-21 ng/ml). Leptin during lactation was lower than in pregnancy but higher than control subjects. Regression analysis suggested that BMI and prolactin can be used as predictors of leptin in pregnancy and lactation. The increase in leptin and prolactin early in pregnancy suggests an association between the two hormones. Results of the present studies and research done by other investigators presents a strong role for leptin during pregnancy and lactation. Leptin is regulated by factors other than adiposity especially in reproductive women leading to our hypothesis that there are leptin and prolactin mediated effects on substrates used for energy utilization during pregnancy and lactation.     

The effects of the menstrual cycle, pregnancy and early lactation on haematology and plasma biochemistry in the baboon (Papio hamadryas)

The changes in the haematology and clinical biochemistry associated with the different stages of the menstrual cycle, gestation and lactation in the baboon (Papio hamadryas) were evaluated in a prospective longitudinal study. Serial EDTA and heparin blood samples were collected from 12 baboons. Haemoglobin concentration, haematorcrit, red blood cell and white blood cell counts were decreased in the luteal compared to the follicular phase (P<0.001); the reverse effect was observed for platelet count, total protein and albumin concentrations. The changes in plasma concentrations of sodium, potassium, urea, creatinine and cholesterol and plasma osmolality were characterized by reductions (P<0.01) in early pregnancy which were maintained throughout gestation. Plasma concentrations of total protein, albumin and alkaline phosphatase, as well as haemoglobin, haematocrit and red cell count were reduced (P<0.001) from mid-gestation. Platelet count and plasma calcium concentration fell continuously throughout gestation (P<0.001). Plasma triglycerides were lower and plasma iron was higher (P<0.01) in gestation compared to the phases of the menstrual cycle and lactation. By 1 week post partum, all parameters except haemaglobin had returned to pre-conception levels.     

Effects of dietary energy intake during gestation and lactation on milk yield and composition of first,second and fourth parity sows

Abstract

In order to determine the effects of a varied level of dietary energy intake during pregnancy and lactation on milk yield and composition, first, second and fourth parity sows (Large White × German Landrace) were provided with energy at a level of either: (i) 100% of ME requirement (MEreq) during pregnancy and lactation, (ii) 120% MEreq during pregnancy and 80% during lactation, and (iii) 80% MEreq during pregnancy and 120% during lactation. In spite of equal target levels feed analysis revealed that gestating first parity sows with 120/80 treatment combination and lactating sows of 80/120 treatment combination received 25, and 11 – 17% more digestible N than in the respective 100/100 treatment combination. Irrespective of this 120/80 sows responded with the highest milk DM, fat, and energy contents, and the lowest lactose concentrations whereas protein levels where not affected, irrespective of parity (p < 0.05). Milk yield of sows in 1st and 4th lactation was 85 and 106% of that in 2nd lactation, respectively. Average milk composition was 18.1% DM, 4.9% protein, 6.8% fat, 5.6% lactose, and 0.8% ash. Milk composition changes ceased at day 7 of lactation with a reduction of milk GE and protein, and an increase of lactose content. Concentrations of threonine, arginine, valine, leucine, tyrosine, phenylalanine, cystine, and tryptophan, as well as stearic, oleic, and linoleic acid were higher in colostrum than in milk at later lactation stages. In contrast, laurine, myristic, palmitic, and palmitoleic acids were lower concentrated in colostrum. In conclusion, these results illustrate the importance of body reserve mobilization for milk production in sows and indicate that low energy supply during gestation cannot be compensated by higher energy supply during lactation.     

Effect of oxytocin on plasma concentrations of 13,14-dihydro-15-keto-prostaglandin F2 alpha during the oestrous cycle and early pregnancy in the goat.

The effect of subcutaneous oxytocin on plasma concentrations of 13,14-dihydro-15-keto-prostaglandin (PG) F2 alpha (PGFM) was examined in the goat at various periods during the oestrous cycle and early pregnancy. 100 i.u. oxytocin was administered daily for 4 day, the dose being divided and given at 0900 and 2100 h; PGFM concentrations were assessed after the first treatment of each day. On days 3-6 (oestrus, day 0) PGFM concentrations increased significantly (P less than 0.001) within 15 minutes and both non-pregnant and mated goats exhibited oestrus behaviour by day 7. Significant (P less than 0.01) increases in PGFM were also produced on days 7-10, in both non-pregnant and pregnant goats, but the responses diminished from day 7 to day 10; only one goat (non-pregnant) came into oestrus. There was a marked difference in response between groups, however, during days 12-15. In non-pregnant goats significant (P less than 0.05) increases in PGFM were detected on days 13-15, but in pregnant animals oxytocin was without effect. Similarly, oxytocin did not increase PGFM concentrations on days 17-20 of pregnancy. However, uterine responsiveness reappeared in pregnant goats with significant (P less than 0.01) increases in PGFM on days 24 and 25.