High-protein diet during gestation and lactation affects mammary gland mRNA abundance, milk composition and pre-weaning litter growth in mice

We evaluated the effect of a high-protein diet (HP) on pregnancy, lactational and rearing success in mice. At the time of mating, females were randomly assigned to isoenergetic diets with HP (40% w/w) or control protein levels (C; 20%). After parturition, half of the dams were fed the other diet throughout lactation resulting in four dietary groups: CC (C diet during gestation and lactation), CHP (C diet during gestation and HP diet during lactation), HPC (HP diet during gestation and C diet during lactation) and HPHP (HP diet during gestation and lactation). Maternal and offspring body mass was monitored. Measurements of maternal mammary gland (MG), kidney and abdominal fat pad masses, MG histology and MG mRNA abundance, as well as milk composition were taken at selected time points. HP diet decreased abdominal fat and increased kidney mass of lactating dams. Litter mass at birth was lower in HP than in C dams (14.8 v. 16.8 g). Dams fed an HP diet during lactation showed 5% less food intake (10.4 v. 10.9 g/day) and lower body and MG mass. On day 14 of lactation, the proportion of MG parenchyma was lower in dams fed an HP diet during gestation as compared to dams fed a C diet (64.8% v. 75.8%). Abundance of MG α-lactalbumin, β-casein, whey acidic protein, xanthine oxidoreductase mRNA at mid-lactation was decreased in all groups receiving an HP diet either during gestation and/or lactation. Milk lactose content was lower in dams fed an HP diet during lactation compared to dams fed a C diet (1.6% v. 2.0%). On days 14, 18 and 21 of lactation total litter mass was lower in litters of dams fed an HP diet during lactation, and the pups' relative kidney mass was greater than in litters suckled by dams receiving a C diet. These findings indicate that excess protein intake in reproducing mice has adverse effects on offspring early in their postnatal growth as a consequence of impaired lactational function.     

Impact of fat source and dietary fibers on feed intake,plasma metabolites,litter gain and the yield and composition of milk in sows

Sow lactation diets often include fat sources without considering the impact on digestion, metabolism and performance. Fiber ingredients may reduce feed intake and are often completely excluded from lactation diets, although locally available ingredients may be cost-efficient alternatives to partly replace cereals in lactation diets. Thus, a standard lactation diet low in dietary fiber, and two high-fiber diets based on sugar beet pulp (SBP) or alfalfa meal (ALF) were formulated. The SBP diet was high in soluble non-starch polysaccharides (NSP), whereas ALF being high in insoluble NSP. Each diet was divided in three portions and combined with 3% soybean oil (SOYO), palm fatty acid distillate (PFAD), or glycerol trioctanoate (C8TG) as the dietary fat source. Equal amounts of metabolizable energy were fed to 36 second parity sows from day 105 of gestation and throughout lactation to study the impact on feed intake, plasma metabolites, milk production and litter performance. Backfat thickness and BW of sows were recorded on days 3, 17 and 28 of lactation; blood was sampled on days 3 and 17; milk samples were obtained on days 3, 10, 17 and 24 of lactation; and piglets were weighed on days 2, 7, 14, 21 and 28 of lactation. Litter gain and milk yield during late lactation were greater in sows fed C8TG or SOYO than in sows fed PFAD (P=0.05), whereas loss of BW (P=0.60) and backfat (P=0.70) was unaffected by fat source. Milk protein on days 3 and 10 of lactation were lower in C8TG and SOYO sows, than in PFAD sows (P<0.05). The lowest concentration of plasma lactate on day 3 (P<0.05) and plasma acetate on day 17 (P<0.05) was observed in C8TG sows. Milk yield was unaffected by fiber treatment (P=0.43), whereas milk protein concentration was lowest in ALF sows (P<0.05). Feed intake tended to be lower (P=0.09), and litter gain during the 3^rd week of lactation was decreased (P<0.05) in SBP sows. In conclusion, performance was enhanced in SOYO and C8TG compared with PFAD sows, possibly associated with reduced energy intake in PFAD-fed sows. Furthermore, the SBP diet seemed to impair feed intake and litter gain at peak lactation, suggesting that effects of the dietary fiber fraction on energy intake determines the potential inclusion level of fiber-rich ingredients.     

Perinatal exposure of rats to a maternal diet with varying protein quantity and quality affects the risk of overweight in female adult offspring

The maternal protein diet during the perinatal period can program the health of adult offspring. This study in rats evaluated the effects of protein quantity and quality in the maternal diet during gestation and lactation on weight and adiposity in female offspring. Six groups of dams were fed a high-protein (HP; 47% protein) or normal-protein (NP; 19% protein) isocaloric diet during gestation (_G) using either cow's milk (M), pea (P) or turkey (T) proteins. During lactation, all dams received the NP diet (protein source unchanged). From postnatal day (PND) 28 until PND70, female pups (n=8) from the dam milk groups were exposed to either an NP milk diet (NPM_W) or to dietary self-selection (DSS). All other pups were only exposed to DSS. The DSS design was a choice between five food cups containing HPM, HPP, HPT, carbohydrates or lipids. The weights and food intakes of the animals were recorded throughout the study, and samples from offspring were collected on PND70. During the lactation and postweaning periods, body weight was lower in the pea and turkey groups (NP_G and HP_G) versus the milk group (P<.0001). DSS groups increased their total energy and fat intakes compared to the NPM_W group (P<.0001). In all HP_G groups, total adipose tissue was increased (P=.03) associated with higher fasting plasma leptin (P<.05). These results suggest that the maternal protein source impacted offspring body weight and that protein excess during gestation, irrespective of its source, increased the risk of adiposity development in female adult offspring.     

Both Maternal Over- and Undernutrition During Gestation Increase the Adiposity of Young Adult Progeny in Rats

FIOROTTO, MARTA L, TERESA A DAVIS, PATRICIA SCHOKNECHT, HARRY J MERSMANN AND WILSON G POND. Both maternal over- and undernutrition during gestation increase the adiposity of young adult progeny in rats. ObesRes. 1995;3:131–141. We examined the influence of maternal diet during gestation on the growth and body composition of the progeny. On day 1 of gestation, rat dams were assigned to one of four feeding regimens: free access to standard rodent chow throughout gestation (AL); 20 g feed/day (prebreeding intake) throughout gestation (PB); 10 g feed/day from day 1 to day 14, then ad libitum from day 15 to parturition (RAL); 10 g feed/day from day 1 to 14, then 20 g/day to parturition (RPB). Progeny were fed ad libitum on standard chow diet from 3 to 12 weeks of age; food intake and weight gain were measured over this time. Body composition was measured at 12 weeks. The PB regimen restricted maternal food intake during the third trimester only; the RAL regimen restricted intake by 50% for two trimesters and produced hyperphagia in the third; the RPB regimen restricted intake by 50% for two trimesters, then intake (per unit body weight) was similar to that of AL dams during the third trimester. Litter size and progeny birth, weaning, and 12-week body weights were similar among the four groups. At 12 weeks of age, PB progeny had the highest body fat (per kg fat-free mass), despite similar feed intake during the 9-week postweaning period. The increased fat was proportionally distributed among intra-abdominal and subcutaneous depots. Progeny of RAL, AL, and RPB dams had similar amounts of body fat, but in RAL progeny more fat was present in intra-abdominal depots. The weights of fat-free mass, gastrointestinal tract and hindlimb skeletal muscles were unaffected by maternal diet Restriction of maternal feed intake during the third week of gestation had subtle effects on the body composition of young adult progeny that could not be explained on the basis of differences in postweaning voluntary feed intake.     

3,5,3'-Triiodothyronine administered to rat dams during lactation increases milk yield and triglyceride concentration and hastens pups growth

It is known that lactation induces a mild hypothyroid state in rats and other mammals while thyroid hormone administration increases milk secretion in ruminants. The aim of this study was to investigate the effects of a moderate dose of 3,5,3'-triiodothyronine (T3), administered to rat dams during lactation on pups' growth and milk yield and composition. Primiparous Wistar rats with litters adjusted to 10 pups per dam received either tap water or T3 (75 microg/kg x day) in their drinking water from parturition till weaning. Food and water intake of dams and body weight of dams and pups were measured daily. In other groups of rats with similar treatments, milk yield of dams, macronutrient milk composition, and mammary arteriovenous differences for triglycerides (TG) and glucose were also determined. Dams treated with T3 ingested more food and their pups gained more weight than controls. Milk yield, milk TG concentration and glucose extraction by mammary glands were also higher in T3 treated dams. The results show that compensation of the mild hypothyroidism of the lactating rat may contribute to an increase in milk production and lipid levels, leading to an increase in growth of pups.     

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.     

Increased maternal fat consumption during pregnancy alters body composition in neonatal mice

Maternal overnutrition prior to and during gestation causes pronounced metabolic dysfunction in the adult offspring. However, less is known about metabolic adaptations in the offspring that occur independently of postnatal growth and nutrition. Therefore, we evaluated the impact of excess maternal dietary lipid intake on the in utero programming of body composition, hepatic function, and hypothalamic development in newborn (P0) offspring. Female mice were fed a low-fat (LF) or high-fat (HF) diet and were mated after 4, 12, and 23 wk. A subset of the obese HF dams was switched to the LF diet during the second (DR2) or third (DR3) pregnancies. The HF offspring accrued more fat mass than the LF pups, regardless of duration of maternal HF diet consumption or prepregnancy maternal adiposity. Increased neonatal adiposity was not observed in the DR3 pups. Liver weights were reduced in the HF offspring but not in the DR2 or DR3 pups. Offspring hepatic triglyceride content was reduced in the HF pups, but hepatic inflammation and expression of lipid metabolism genes were largely unaffected by maternal diet. Maternal diet did not alter the hypothalamic expression of orexigenic and anorexigenic neuropeptides in the offspring. Thus, the intrauterine programming of increased neonatal adiposity and reduced liver size by maternal overnutrition is evident in mice at birth and occurs prior to the development of maternal obesity. These observations demonstrate that dietary intervention during pregnancy minimizes the deleterious effects of maternal obesity on offspring body composition, potentially reducing the offsprings' risk of developing obesity and related diseases later in life.     

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.     

Modeling homeorhetic trajectories of milk component yields,body composition and dry-matter intake in dairy cows: Influence of parity,milk production potential and breed

The control of nutrient partitioning is complex and affected by many factors, among them physiological state and production potential. Therefore, the current model aims to provide for dairy cows a dynamic framework to predict a consistent set of reference performance patterns (milk component yields, body composition change, dry-matter intake) sensitive to physiological status across a range of milk production potentials (within and between breeds). Flows and partition of net energy toward maintenance, growth, gestation, body reserves and milk components are described in the model. The structure of the model is characterized by two sub-models, a regulating sub-model of homeorhetic control which sets dynamic partitioning rules along the lactation, and an operating sub-model that translates this into animal performance. The regulating sub-model describes lactation as the result of three driving forces: (1) use of previously acquired resources through mobilization, (2) acquisition of new resources with a priority of partition towards milk and (3) subsequent use of resources towards body reserves gain. The dynamics of these three driving forces were adjusted separately for fat (milk and body), protein (milk and body) and lactose (milk). Milk yield is predicted from lactose and protein yields with an empirical equation developed from literature data. The model predicts desired dry-matter intake as an outcome of net energy requirements for a given dietary net energy content. The parameters controlling milk component yields and body composition changes were calibrated using two data sets in which the diet was the same for all animals. Weekly data from Holstein dairy cows was used to calibrate the model within-breed across milk production potentials. A second data set was used to evaluate the model and to calibrate it for breed differences (Holstein, Danish Red and Jersey) on the mobilization/reconstitution of body composition and on the yield of individual milk components. These calibrations showed that the model framework was able to adequately simulate milk yield, milk component yields, body composition changes and dry-matter intake throughout lactation for primiparous and multiparous cows differing in their production level.     

Influence of maternal dietary calcium levels on milk zinc, calcium and phosphorus contents and milk production in rats

The aim of this study was to analyze zinc (Zn), calcium (Ca) and phosphorus (P) contents in milk and the lactational performance in rats fed different Ca levels. Female Wistar rats were fed during pregnancy and lactation with experimental diets containing 20% protein and high (0.90%, HCa), normal (0.60%, NCa) or low (0.20%, LCa) Ca levels. Milk samples were collected after 15 days to determine the milk mineral composition. Pup weight was recorded from birth to weaning (litter size: 6-8 pups) to determine weight gain and calculate milk production. At delivery there were no significant differences in the body weight of the pups between the groups, but at day 15, the LCa group showed lower values than both NCa and HCa groups (p<0.05). The weight gain of the LCa group was significantly lower than of the HCa and NCa groups, between delivery and day 5 (p<0.05). This reduced rate of weight gain led to the LCa group reaching weaning weight later than the other groups. Milk production (g/pup/day) was significantly lower when dams were fed the LCa than the NCa and HCa diets (p<0.05). There were no significant differences among the groups in milk Ca, P and Zn levels and Ca/P ratio. The body mineral composition of the pups at birth did not differ between the groups; at weaning, however, both LCa and HCa groups had lower element contents than the NCa group (p<0.05). In conclusion, dams fed with a diet containing low Ca levels produced smaller volumes of milk and their pups reached weaning weights later than the other groups. As the milk mineral composition was not affected, it can be hypothesized that in dams fed low dietary Ca, the smaller milk yield might have been a way of maintaining milk quality. High Ca levels affected neither pregnancy outcome nor lactational performance.     

Maternal Dietary Supplementation with Oligofructose-Enriched Inulin in Gestating/Lactating Rats Preserves Maternal Bone and Improves Bone Microarchitecture in Their Offspring

Nutrition during pregnancy and lactation could exert a key role not only on maternal bone, but also could influence the skeletal development of the offspring. This study was performed in rats to assess the relationship between maternal dietary intake of prebiotic oligofructose-enriched inulin and its role in bone turnover during gestation and lactation, as well as its effect on offspring peak bone mass/architecture during early adulthood. Rat dams were fed either with standard rodent diet (CC group), calcium-fortified diet (Ca group), or prebiotic oligofructose-enriched inulin supplemented diet (Pre group), during the second half of gestation and lactation. Bone mineral density (BMD) and content (BMC), as well as micro-structure of dams and offspring at different stages were analysed. Dams in the Pre group had significantly higher trabecular thickness (Tb.Th), trabecular bone volume fraction (BV/TV) and smaller specific bone surface (BS/BV) of the tibia in comparison with CC dams. The Pre group offspring during early adulthood had an increase of the lumbar vertebra BMD when compared with offspring of CC and Ca groups. The Pre group offspring also showed significant increase versus CC in cancellous and cortical structural parameters of the lumbar vertebra 4 such as Tb.Th, cortical BMD and decreased BS/BV. The results indicate that oligofructose-enriched inulin supplementation can be considered as a plausible nutritional option for protecting against maternal bone loss during gestation and lactation preventing bone fragility and for optimizing peak bone mass and architecture of the offspring in order to increase bone strength.     

Urea concentration in collared peccary milk as an indicator of protein nutritional status

Milk urea nitrogen (UN) concentration was examined as a possible index to protein-energy intake in female collared peccaries (Tayassu tajacu). Captive adults were bred and assigned to one of four experimental diets through gestation and lactation. Females fed a high protein diet produced milk with UN concentrations exceeding those of low-protein-fed females. A low energy intake tended to elevate UN concentrations in milk.     

High-unsaturated-fat, high-protein, and low-carbohydrate diet during pregnancy and lactation modulates hepatic lipid metabolism in female adult offspring

Whether a high-unsaturated-fat, high-protein (HFP), and low-carbohydrate (CHO) diet during gestation has long-lasting beneficial effects on lipid metabolism in the offspring was investigated using a mouse model. Female mice were fed either a standard (CHO rich) chow diet or a CHO HFP diet, before and during gestation and lactation. All offspring were weaned onto the same chow until adulthood. Although liver cholesterol concentration and fasting plasma triglyceride (TG), cholesterol, and free fatty acid concentrations were not affected in either male or female HFP offspring, hepatic TG concentration was reduced by approximately 51% (P < 0.05) in the female adult offspring from dams on the HFP diet, compared with females from dams on the chow diet (a trend toward reduced TG concentration was also observed in the male). Furthermore, hepatic protein levels for CD36, carnitine palmitoyltransferase-1 (CPT-1), and peroxisomal proliferator activated receptor-alpha (PPAR-alpha) were increased by approximately 46% (P < 0.001), approximately 52% (P < 0.001), and approximately 14% (P = 0.035), respectively, in the female HFP offspring. Liver TG levels were negatively correlated with protein levels of CD 36 (r = -0.69, P = 0.007), CPT-1 (r = -0.55, P = 0.033), and PPAR-alpha (r = -0.57, P = 0.025) in these offspring. In conclusion, a maternal HFP diet during gestation and lactation reduces hepatic TG concentration in female offspring, which is linked with increased protein levels in fatty acid oxidation.     

Feeding of soy protein isolate to rats during pregnancy and lactation suppresses formation of aberrant crypt foci in their progeny's colons: interaction of diet with fetal alcohol exposure

Soy protein isolate (SPI) in the diet may inhibit colon tumorigenesis. We examined azoxymethane (AOM)-induced aberrant crypt foci (ACF) in male rats in relation to lifetime, pre-weaning, or post-weaning dietary exposure to SPI and also within the context of fetal alcohol exposure. Pregnant Sprague Dawley rats were fed AIN-93G diets containing casein (20%, the control diet) or SPI (20%) as the sole protein source starting on gestation day 4 (GD 4). Progeny were weaned on postnatal day (PND) 21 to the same diet as their dams and were fed this diet until termination of the experiment at PND 138. Rats received AOM on PND 89 and 96. Lifetime (GD 4 to PND 138) feeding of SPI led to reduced frequency of ACF with 4 or more crypts in the distal colon. Progeny of dams fed SPI only during pregnancy and lactation or progeny fed SPI only after weaning exhibited similarly reduced frequency of large ACF in distal colon. Number of epithelial cells, in the distal colon, undergoing apoptosis was unaffected by diet. SPI reduced weight gain and adiposity, but these were not correlated with fewer numbers of large ACF. Lifetime SPI exposure similarly inhibited development of large ACF in Sprague Dawley rats whose dams were exposed to ethanol during pregnancy. In summary, feeding of SPI to rat dams during pregnancy and lactation suppresses numbers of large ACF in their progeny, implying a long-term or permanent change elicited by the maternal diet. Moreover, results support the use of ACF as an intermediate endpoint for elucidating effects of SPI and its biochemical constituents in colon cancer prevention in rats.     

Utilization of milk energy by suckling mink kits

A total of 36 mink dams and their litters of 3, 6 or 9 kits were used for determination of milk intake of the suckling young by means of deuterium dilution technique, and chemical composition of milk and of kit bodies. Measurements were performed during lactation weeks 1-4, each week with 3 dams with each litter size. Milk intake was determined over a 48 h measurement period, and by the end of this milk samples were collected and 2 kits (litters of 6 and 9) or 1 kit per litter (litters of 3) were killed for body chemical composition. Based on the results, different models were applied for calculation of the energetic efficiency of milk. Dam milk yield increased steadily from week 1 until week 3 but only slightly from week 3 to 4. The increase declined with increasing litter size, and for dams suckling 9 kits the increment from week 3 to week 4 was only 2 g. The dry matter content of milk increased significantly as lactation progressed, being reflected in crude protein increasing from 6.9% in lactation week 1 to 8.1% in week 4. Milk fat increased concomitantly from 5.6% to 8.0%. In kit bodies, crude protein content increased from 9.4% in week 1 to about 12% in weeks 3 and 4. Body fat content increased from week 1 (4.1%) to week 3 (8.4%) and then declined in week 4 (7.1%). Animals suckled in litters of 3 kits had the highest milk intake and live weight and kits suckled in litters of 9 had the lowest milk intake, live weight and daily gain. In terms of milk intake per g gain kits in litters of 6 were the most efficient, with 4.1 g milk per g body gain. The metabolizable energy requirement for maintenance (MEm) was estimated to 448 kJ/kg(0.75 and the efficiency of utilization of ME for body gain (kg) to 0.67, the estimates being higher (MEm) or in good agreement with previous findings (kg) in suckling mink kits.     

The effect of exogenous prolactin on lactation performance of first-litter sows given protein-deficient diets during the first pregnancy

Twenty-four sows were used to study the effects of dietary protein restriction during pregnancy and exogenous porcine prolactin (pPRL) during late pregnancy and throughout lactation on lactation performance. Eight sows were given a protein-adequate diet containing 179 g crude protein (CP)kg⁻¹ during their first pregnancy while the remaining 16 sows received the same amount of a diet containing 80 g CP kg⁻¹. Eight of the sows given 80 g CP kg⁻¹ during pregnancy were injected with 15 mg pPRL i.m. twice daily at 08:00 and 20:00 between day (d) 102.1 (±0.3) of pregnancy and weaning after their first lactation. Pregnant sows offered the low protein diet gained significantly less body weight during gestation and tended to eat less in the subsequent lactation than sows given the protein-adequate diet. Dietary protein had no significant effect on birth weight, milk yield, milk composition or growth rate of the litter during lactation. Neither dietary protein intake during pregnancy nor exogenous prolactin affected the concentrations of plasma glucose, serum insulin, urea or non-esterified fatty acid (NEFA) during lactation. The concentration of lactose in plasma during lactation was unaffected by treatment, but at d 105 of pregnancy, plasma lactose levels were greater in sows which had received exogenous prolactin (32.4 vs. 6.2 mg l⁻¹, P < 0.05). The concentrations of RNA and DNA in mammary tissue biopsies were unaffected by either dietary protein or pPRL. The concentration of RNA and DNA increased between d 70 and 90 from 0.66 to 2.77 mg g⁻¹ and from 0.54 to 1.19 mg g⁻¹, respectively. Thereafter, RNA increased to 4.40 mg g⁻¹ at d 14 of lactation whilst DNA concentration remained at a similar level of 0.90 mg g⁻¹.Milk yield of sows between d 5 and 8 and between d 19 and 22 of lactation was reduced from 8.36 to 7.00 kg day⁻¹ and from 10.74 to 8.22 kg day⁻¹, respectively, in sows given pPRL. The protein content of colostrum from sows treated with pPRL was reduced from 164 to 104 g kg⁻¹ whereas the fat content increased from 47 to 127 g kg⁻¹. These results indicate that the administration of exogenous pPRL during late pregnancy and throughout lactation initiated lactogenesis prematurely and reduced subsequent milk yield during established lactation.     

Leptin levels in rat offspring are modified by the ratio of linoleic to alpha-linolenic acid in the maternal diet

The supply of polyunsaturated fatty acids (PUFA) is important for optimal fetal and postnatal development. We have previously shown that leptin levels in suckling rats are reduced by maternal PUFA deficiency. In the present study, we evaluated the effect of maternal dietary intake of (n-3) and (n-6) PUFA on the leptin content in rat milk and serum leptin levels in suckling pups. For the last 10 days of gestation and throughout lactation, the rats were fed an isocaloric diet containing 7% linseed oil (n-3 diet), sunflower oil (n-6 diet), or soybean oil (n-6/n-3 diet). Body weight, body length, inguinal fat pad weight, and adipocyte size of the pups receiving the n-3 diet were significantly lower during the whole suckling period compared with n-6/n-3 fed pups. Body and fat pad weights of the n-6 fed pups were in between the other two groups at week one, but not different from the n-6/n-3 group at week 3. Feeding dams the n-3 diet resulted in decreased serum leptin levels in the suckling pups compared with pups in the n-6/n-3 group. The mean serum leptin levels of the n-6 pups were between the other two groups but not different from either group. There were no differences in the milk leptin content between the groups. These results show that the balance between the n-6 and n-3 PUFA in the maternal diet rather than amount of n-6 or n-3 PUFA per se could be important for adipose tissue growth and for maintaining adequate serum leptin levels in the offspring.     

Maternal and fetal growth, body composition, endocrinology, and metabolic status in undernourished adolescent sheep

The influence of relative maternal undernutrition on growth, endocrinology, and metabolic status in the adolescent ewe and her fetus were investigated at Days 90 and 130 of gestation. Singleton pregnancies to a single sire were established, and thereafter ewes were offered an optimal control (C; n = 14) or low (L [0.7 x C]; n = 21) dietary intake. Seven ewes receiving the L intake were switched to the C intake on Day 90 of gestation (L-C). At Day 90, live weight and adiposity score were reduced (P < 0.001) in L versus C dams. Plasma insulin and IGF1 concentrations were decreased (P < 0.02), whereas glucose concentrations were preserved in L relative to C intake dams. Fetal and placental mass was independent of maternal nutrition at this stage. By Day 130 of gestation, when compared to C and L-C dams, maternal adiposity was further depleted in L intake dams; concentrations of insulin, IGF1, and glucose were reduced; and nonesterified fatty acids increased. At Day 130, placental mass remained independent of maternal nutrition, but body weight was reduced (P < 0.01) in L compared with C fetuses (3555 g vs. 4273 g). Body weight was intermediate (3836 g) in L-C fetuses. Plasma glucose (P < 0.03), insulin (P < 0.07), and total liver glycogen content (P < 0.04) were attenuated in L fetuses. Fetal carcass analyses revealed absolute reductions (P < 0.05) in dry matter, crude protein, and fat, and a relative (g/kg) increase in carcass ash (P < 0.01) in L compared with C fetuses. Thus, limiting maternal intake during adolescent pregnancy gradually depleted maternal body reserves, impaired fetal nutrient supply, and slowed fetal soft tissue growth.     

Utilization of milk energy by suckling mink kits

A total of 36 mink dams and their litters of 3, 6 or 9 kits were used for determination of milk intake of the suckling young by means of deuterium dilution technique, and chemical composition of milk and of kit bodies. Measurements were performed during lactation weeks 1?–?4, each week with 3 dams with each litter size. Milk intake was determined over a 48?h measurement period, and by the end of this milk samples were collected and 2 kits (litters of 6 and 9) or 1 kit per litter (litters of 3) were killed for body chemical composition. Based on the results, different models were applied for calculation of the energetic efficiency of milk. Dam milk yield increased steadily from week 1 until week 3 but only slightly from week 3 to 4. The increase declined with increasing litter size, and for dams suckling 9 kits the increment from week 3 to week 4 was only 2?g. The dry matter content of milk increased significantly as lactation progressed, being reflected in crude protein increasing from 6.9% in lactation week 1 to 8.1% in week 4. Milk fat increased concomitantly from 5.6% to 8.0%. In kit bodies, crude protein content increased from 9.4% in week 1 to about 12% in weeks 3 and 4. Body fat content increased from week 1 (4.1%) to week 3 (8.4%) and then declined in week 4 (7.1%). Animals suckled in litters of 3 kits had the highest milk intake and live weight and kits suckled in litters of 9 had the lowest milk intake, live weight and daily gain. In terms of milk intake per g gain kits in litters of 6 were the most efficient, with 4.1?g milk per g body gain. The metabolizable energy requirement for maintenance (MEm) was estimated to 448 kJ/kg^0.75 and the efficiency of utilization of ME for body gain (k_g) to 0.67, the estimates being higher (MEm) or in good agreement with previous findings (k_g) in suckling mink kits.     

Gestational changes in concentrations of selenium and zinc in the porcine fetus and the effects of maternal intake of selenium

The effect of maternal dietary selenium (Se) and gestation on the concentrations of Se and zinc (Zn) in the porcine fetus were determined. Mature gilts were randomly assigned to treatments of either adequate (0.39 ppm Se) or low (0.05 ppm Se) dietary Se. Gilts were bred and fetuses were collected throughout gestation. Concentrations of Se in maternal whole blood and liver decreased during gestation in sows fed the low-Se diet compared to sows fed the Se-supplemented diet. Maternal intake of Se did not affect the concentration of Se in the whole fetus; however, the concentration of Se in fetal liver was decreased in fetuses of sows fed the low-Se diet. Although fetal liver Se decreased in both treatments as gestation progressed, the decrease was greater in liver of fetuses from sows fed the low-Se diet. Dietary Se did not affect concentrations of Zn in maternal whole blood or liver or in the whole fetus and fetal liver. The concentration of Se in fetal liver was lower but the concentration of Zn was greater than in maternal liver when sows were fed the adequate Se diet. These results indicate that maternal intake of Se affects fetal liver Se and newborn piglets have lower liver Se concentrations compared to their dams, regardless of the Se intake of sows during gestation. Thus, the piglet is more susceptible Se deficiency than the sow.