Characterization of proteins and fatty acid composition in Galapagos fur seal milk. Occurrence of whey and casein protein polymorphisms

1. Milk proteins of the Galapagos fur seal (Arctocephalus galapagoensis) were separated adequately into whey and casein fractions using bovine milk analysis methods. 2. In samples from days 5-30 of lactation 40% of the total proteins were whey and 60% caseins; in mid-lactation, day 150, 25% were whey and 75% casein proteins. 3. Electrophoretic and isoelectric focusing patterns of fur seal whey protein differed widely from bovine patterns, whereas those of caseins were similar. 4. Polymorphisms of fur seal whey and casein proteins were noted and did not seem related to different stages of lactation. 5. C-16 and C-18 fatty acids contributed about 70% of fatty acids; 63% of the total acids in milk fat were unsaturated.     

Alterations in the milk yield and composition during different stages of lactation cycle in elite and non-elite Karan-Fries cross-bred cows (Holstein Fresian x Tharparkar)

Alterations in the milk constituents throughout the lactation cycle have been studied in 20 Karan-Fries cross-bred cows (Holstein Fresian x Tharparkar) divided into two groups, viz. elite (n = 10) and non-elite (n = 10). About 100 ml of composite milk samples (from all the quarters) were collected through hand milking in sterile tubes from the day of calving at 15-day interval till 300 days of lactation cycle. Different milk constituents (viz. fat, protein, lactose, Solid not fat) were estimated by automatic milk analyzer. The daily milk yield varied significantly (p < 0.01) between group and different days of lactation cycle. Milk fat percentage of milk did not differ significantly between groups and different days of lactation cycle. Milk protein and lactose percentage did not differ significantly between groups but differed significantly (p < 0.001) between days. Solid not fat (SNF) percentage of milk was significantly (p < 0.01) higher in elite cows compared to non-elite cows and also varied significantly (p < 0.05) during different days of lactation cycle. In both the group of cows, milk protein, fat, and SNF percentage was highest and lactose percentage was lowest up to 1st week of lactation cycle and rapidly declined thereafter due to the transition of the colostrum into milk. After 2nd week of lactation, all the milk constituents under study were almost remained unaltered till the end of the cycle. The above stated investigation not only substantiates the already existing information of lactation stage-specific alteration in milk constituents but also depict the exact point of transition of these constituents during the lactation cycle so the nutritional and managemental interventions could be carried out in proper time.     

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.     

Mammary Specific Transgenic Over-expression of Insulin-like Growth Factor-I (IGF-I) Increases Pig Milk IGF-I and IGF Binding Proteins,with no Effect on Milk Composition or Yield

IGF-I regulates lactation by stimulating mammary mitogenesis, inhibiting apoptosis, and partially mediating the effects of growth hormone on lactogenesis. Herein, lactation performance during first and second parity was assessed in transgenic swine (TG) that over-expressed human IGF-I in milk under the control of the bovine α-lactalbumin promoter, regulatory regions and signal peptide coding sequence. Milk samples were collected throughout lactation (farrowing to d24) from TG sows and non-transgenic littermates (CON) and IGF-I, IGF-II, and IGFBP determined. Colostral (<24 h postpartum) IGF-I content was 26-fold greater (p < 0.001) in TG sows (949 ± 107 μg/L; range 228–1600 μg/L) than CON (36 ± 17.8 μg/L) and was 50- to 90-fold greater (p < 0.001) in mature milk (d2-24 postpartum). There was no effect of parity on milk IGF-I content. Milk IGF-II concentration was unaffected by IGF-I over-expression. Low molecular weight IGFBP (IGFBP-2 and -5) in the milk of TG sows were higher (p = 0.02) than CON in the early postpartum period, but did not differ in mature milk. Milk yield, determined by weigh-suckle-weigh, was similar in TG and CON as was litter weight gain. Milk nutrient composition was not significantly affected by IGF over-expression. Thus, mammary specific transgenic over-expression of IGF-I significantly increased milk IGF-I and IGFBP content, but did not impact lactation performance in swine.     

Supplementing sow diets with palm oil during late gestation and lactation: effects on milk production,sow hormonal profiles and growth and development of her offspring

The supplementing of sow diets with lipids during pregnancy and lactation has been shown to reduce sow condition loss and improve piglet performance. The aim of this study was to determine the effects of supplemental palm oil (PO) on sow performance, plasma metabolites and hormones, milk profiles and pre-weaning piglet development. A commercial sow ration (C) or an experimental diet supplemented with 10% extra energy in the form of PO, were provided from day 90 of gestation until weaning (24 to 28 days postpartum) in two groups of eight multiparous sows. Gestation length of PO sows increased by 1 day (P<0.05). Maternal BW changes were similar throughout the trial, but loss of backfat during lactation was reduced in PO animals (C: −3.6±0.8 mm; PO: −0.1±0.8 mm; P<0.01). Milk fat was increased by PO supplementation (C day 3: 8.0±0.3% fat; PO day 3: 9.1±0.3% fat; C day 7: 7.8±0.5% fat; PO day 7: 9.9±0.5% fat; P<0.05) and hence milk energy yield of PO sows was also elevated (P<0.05). The proportion of saturated fatty acids was greater in colostrum from PO sows (C: 29.19±0.31 g/100 g of fat; PO: 30.77±0.36 g/100 g of fat; P<0.01). Blood samples taken on 105 days of gestation, within 24 h of farrowing, day 7 of lactation and at weaning (28±3 days post-farrowing) showed there were no differences in plasma concentrations of triacylglycerol, non-esterified fatty acids, insulin or IGF-1 throughout the trial. However, circulating plasma concentrations of both glucose and leptin were elevated during lactation in PO sows (P<0.05 and P<0.005, respectively) and thyroxine was greater at weaning in PO sows (P<0.05). Piglet weight and body composition were similar at birth, as were piglet growth rates throughout the pre-weaning period. A period of 7 days after birth, C piglets contained more body fat, as indicated by their lower fat-free mass per kg (C: 66.4±0.8 arbitrary units/kg; PO: 69.7±0.8 arbitrary unit/kg; P<0.01), but by day 14 of life this situation was reversed (C: 65.8±0.6 arbitrary units/kg; PO: 63.6±0.6 arbitrary units/kg; P<0.05). Following weaning, PO sows exhibited an increased ratio of male to female offspring at their subsequent farrowing (C: 1.0±0.3; PO: 2.2±0.2; P<0.05). We conclude that supplementation of sow diets with PO during late gestation and lactation appears to increase sow milk fat content and hence energy supply to piglets. Furthermore, elevated glucose concentrations in the sow during lactation may be suggestive of impaired glucose homoeostasis.     

Serum Electrolyte and Mineral Variations During Pregnancy and Lactation in Nili-Ravi Buffalo

The aim of present study was to determine the changes of sodium, potassium, chloride, copper, and zinc in serum of Nili-Ravi buffalo during pregnancy and lactation. The study was carried out on 25 Nili-Ravi buffaloes during March 2008 to February 2009 at Buffalo Research Institute, Pattoki, District Kasur. Blood samples were taken from each buffalo during early pregnancy (Phase EP), i.e., between 1 and 3 months gestation, mid pregnancy (Phase MP), i.e., between 4 and 6 months gestation, late pregnancy (Phase LP), i.e., between 7 and 10 months gestation, and during lactation (Phase LT). Serum sodium, potassium, and chloride were determined on a clinical chemistry analyzer whereas copper and zinc were determined on an atomic absorption spectrophotometer. The mean serum sodium, potassium, and chloride concentrations varied non-significantly (P > 0.05) during pregnancy and lactation. With advancing pregnancy, copper increased and was significantly high (P < 0.05) during late pregnancy whereas during lactation copper concentrations dropped significantly (P < 0.05). The zinc concentrations increased non-significantly during early and mid pregnancy. There were significant differences (P < 0.05) in zinc concentrations during lactation compared with late pregnancy. This study demonstrates that concentrations of serum sodium, potassium, and chloride remain unchanged during pregnancy and lactation whereas serum copper concentrations increased and zinc concentrations decreased with advancing pregnancy because of the demand of the fetus at different periods of pregnancy.     

Increased dietary protein for lactating sows affects body composition,blood metabolites and milk production

Hyper-prolific sows nurse more piglets than less productive sows, putting a high demand on the nutrient supply for milk production. In addition, the high production level can increase mobilization from body tissues. The effect of increased dietary protein (104, 113, 121, 129, 139 and 150 g standardized ileal digestible (SID) CP/kg) on sow body composition, milk production and plasma metabolite concentrations was investigated from litter standardization (day 2) until weaning (day 24). Sow body composition was determined using the deuterium oxide dilution technique on days 3 and 24 postpartum. Blood samples were collected weekly, and milk samples were obtained on days 3, 10 and 17 of lactation. Litter average daily gain (ADG) peaked at 135 g SID CP/kg (P < 0.001). Sow BW and back fat loss reached a breakpoint at 143 and 127 g SID CP/kg (P < 0.001). Milk fat increased linearly with increasing dietary SID CP (P < 0.05), and milk lactose decreased until a breakpoint at 124 g SID CP/kg and 5.3% (P < 0.001) on day 17. The concentration of milk protein on day 17 increased until a breakpoint at 136 g SID CP/kg (5.0%; P < 0.001). The loss of body protein from day 3 until weaning decreased with increased dietary SID CP until it reached a breakpoint at 128 g SID CP/kg (P < 0.001). The body ash loss declined linearly with increasing dietary SID CP (P < 0.01), and the change in body fat was unaffected by dietary treatment (P=0.41). In early lactation (day 3 + day 10), plasma urea N (PUN) increased linearly after the breakpoint at 139 g SID CP/kg at a concentration of 3.8 mmol/l, and in late lactation (day 17 + day 24), PUN increased linearly after a breakpoint at 133 g SID CP/kg (P < 0.001) at a concentration of 4.5 mmol/l. In conclusion, the SID CP requirement for sows was estimated to 135 g/kg based on litter ADG, and this was supported by the breakpoints of other response variables within the interval 124 to 143 g/kg.     

Alterations in the relative abundance of Haptoglobin (Hp) transcripts in total milk somatic cells during different stages of lactation cycle in high yielding cross-bred cows

The expression profile of Haptoglobin (Hp) gene in total milk somatic cells (SCC) of high-yielding cross-bred Karan Fries (KF) was studied during early, mid, and late lactation cycle. Milk samples (200 ml/animals) were collected from 10 high-yielding and 10 low-yielding cows throughout the lactation cycle (from day 7 to day 300) with an interval of one month. Relative mRNA expression profiles of Hp by RT polymerase chain reaction was studied in high-yielding cows, whereas low-yielding cows were taken as control. The folds of induction of Hp was significantly (p < 0.001) downregulated by a mean factor of 0.207 in milk SCC during early lactating cows. Whereas, it was significantly (p < 0.01) upregulated by a mean factor of 20.888 during mid lactation. The expression was unaltered during the late lactation. The study demonstrates that Hp is synthesized within the mammary gland and significantly upregulated during mid-lactation period compared to other stages of lactation cycle.     

Association of genetic polymorphism inGH gene with milk production traits in Beijing Holstein cows

Associations were analysed between polymorphisms of the growth hormone gene (GH-MspI) (localized in intron 3) and milk production traits of Beijing Holstein cows (a total of 543 cows). Polymerase chain reaction (PCR)-restriction fragment length polymorphism (RFLP) method was used for identification of various geno-types. Frequencies of genotypes were 0.77, 0,21 and 0.02 for A/A, A/B and B/B, respectively. The frequency of theGH ^A allele is 0.875. The results of the least squares means show that in all three lactations, theGH A/A cows yielded more milk (P < 0.01 for lactation I andP 0.05 for lactations II and III), whereas A/B cows showed higher milk fat content than A/A individuals (P < 0.05 for lactations I and II, andP < 0.01 for lactation III). The A/A cows yielded more fat than A/B individuals (P < 0.01 only in lactation I). The A/A cows yielded more milk protein than A/B individuals (P < 0.01 for lactations I, II, and III). The A/A cows produced milk of higher protein content than of A/B individuals (P < 0.05 only in lactation II).     

Milk protein composition in purebred Holsteins and in first/second-generation crossbred cows from Swedish Red,Montbeliarde and Brown Swiss bulls

The aim of this study was to analyze milk protein composition in purebred and crossbred dairy cattle and estimate the effects of individual sources of variation on the investigated traits. Milk samples were collected from 505 cows from three commercial farms located in Northern Italy, some of which had originated from crossbreeding programs, although most were purebred Holsteins (HO). The basic crossbreeding scheme was a three-breed rotational system using Swedish Red (SR) semen on HO cows (SR×HO), Montbeliarde (MO) semen on SR×HO cows (MO×(SR×HO)) and HO semen again on MO×(SR×HO) cows. A smaller number of purebred HO from each of the herds were mated inverting the breed order (MO×HO and SR×(MO×HO)) or using Brown Swiss (BS) bulls (BS×HO) then MO bulls (MO×(BS×HO)). Milk samples were analyzed by reverse-phase HPLC to obtain protein fraction amounts (g/l) and proportions (% of total true protein). Traits were analyzed using a linear model, which included the fixed effects of herd-test-day (HTD), parity, days in milk and breed combination. Results showed that milk protein fractions were influenced by HTD, stage of lactation, parity and breed combination. The increase in protein concentration during lactation was due in particular to β-casein (β-CN), α_S1-CN and β-lactoglobulin (β-LG). The higher protein content of primiparous milk was mainly due to higher concentrations of all casein fractions. The milk from crossbred cows had higher contents and proportions of κ-CN and α-lactalbumin (α-LA), lower proportions of β-LG and greater proportion of caseins/smaller in whey proteins on milk true protein than purebred HO. The three-way crossbreds differed from two-way crossbreds only in having greater proportions of α-LA in their milk. Of the three-way crossbreds, the SR sired cows yielded milk with a smaller content and proportion of β-LG than the MO sired cows, and, consequently, a higher proportion of caseins than whey proteins. Results from this study support the feasibility of using crossbreeding programs to alter milk protein profiles with the aim of improving milk quality and cheese-making properties.     

Proteomic analysis of whey and casein proteins in early milk from the marsupial Trichosurus vulpecula,the common brushtail possum

Whey and casein proteins representing the first and second halves of the early lactation phase in the common brushtail possum (Trichosurus vulpecula) have been compared by two dimensional gel electrophoresis. Nine components of whey were differentially expressed during early lactation, including proteins identified as cathepsin B, clusterin, late lactation protein, lysozyme, ganglioside M2 activator and neutrophil gelatinase-associated lipocalin. A major novel protein, termed very early lactation protein (VELP), was identified in whey. Partial amino acid sequence data obtained from VELP did not appear to match any other reported protein sequence. VELP was shown to be an acidic glycoprotein of 20–30 kDa which exists as a homodimer. In the casein fraction, κ-casein appeared to be differentially post-translationally modified during early lactation and fragments of β-casein were relatively more abundant at the earlier lactation stage.     

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.     

Plasma prolactin,blood metabolites and milk production in bromocryptine-treated crossbred goats

To determine the effect of bromocryptine on plasma prolactin, metabolites and milk production, six healthy crossbred goats in their second or third lactation were selected from the institute’s goat herd. The goats were injected with bromocryptine @ 5 mg per day intramuscularly for a period of 5 days during 55–60 days of lactation (period I) and treatment was repeated after 14 days for an additional 5 days (period II). Blood samples were collected for 5 consecutive days before, during and after administration of bromocryptine during both periods of the study. Milk samples were collected on days coinciding with the days of blood sampling. During period I, bromocryptine administration decreased (P < 0.01) milk yields by 27.4%. After withdrawal of bromocryptine the yields increased (P < 0.01); however, during period II, bromocryptine treatment did not decrease milk yields. During period I bromocryptine treatment suppressed prolactin level (P < 0.01) which coincided with decrease in milk yield, but in period II such decreases in prolactin did not coincide with changes in milk yields. Fat content increased (P < 0.01) after bromocryptine administration in both periods. A decrease (P < 0.01) in protein and lactose content indicated a possible role of prolactin in the synthesis of these constituents by the mammary gland cell in goats. Blood glucose and NEFA were not affected by bromocryptine in period I but in period II an increase in blood glucose with a simultaneous decrease in NEFA was observed (P < 0.01).From this study it is concluded that prolactin has a role in the maintenance of milk secretion through protein synthesis by the mammary gland. However, it does not seem to have any direct role on milk fat synthesis.     

Variation in blood leucocytes,somatic cell count,yield and composition of milk of crossbred goats

Ten multiparous crossbred goats, five each of alpine × beetal (AB) and saanen × beetal (SB) were selected from the National Dairy Research Institute goat herd immediately after parturition. These were managed as per the practices followed in the institute’s goatherd. Blood and milk samples were collected at biweekly intervals from day 14 post-kidding for 22 weeks (154 days). Somatic cell count, electrical conductivity, fat, protein and lactose contents of milk were determined using standard methods. In the blood samples total leucocytes and differential leucocytes were also determined. Somatic cell counts were high immediately after parturition on day 14 of lactation and declined gradually with advanced lactation. There were individual variations (P < 0.01) in somatic cell counts between different lactation periods. Somatic cell count of milk was negatively correlated with neutrophils only (P < 0.05) and was neither correlated with milk yield, or with fat, protein, lactose content of milk. Electrical conductivity of milk was low up to four weeks of lactation and thereafter increased as the lactation advanced. Lactose content of milk declined gradually with the advancement of lactation. Fat content of milk was stable up to the eighth week and thereafter increased with advancement of lactation while the protein content of milk did not change significantly during lactation.     

Secretion of whey acidic protein and cystatin is down regulated at mid-lactation in the red kangaroo (Macropus rufus)

Milk collected from the red kangaroo (Macropus rufus) between day 100 and 260 of lactation showed major changes in milk composition at around day 200 of lactation, the time at which the pouch young begins to temporarily exit the pouch and eat herbage. The carbohydrate content of milk declined abruptly at this time and although there was only a small increase in total protein content, SDS PAGE analysis of milk revealed asynchrony in the secretory pattern of individual proteins. The levels of alpha-lactalbumin, beta-lactoglobulin, serum albumin and transferrin remain unchanged during lactation. In contrast, the protease inhibitor cystatin, and the putative protease inhibitor whey acidic protein (WAP) first appeared in milk at elevated concentrations after approximately 150 days of lactation and then ceased to be secreted at approximately 200 days. In addition, a major whey protein, late lactation protein, was first detected in milk around the time whey acidic protein and cystatin cease to be secreted and was present at least until day 260 of lactation. The co-ordinated, but asynchronous secretion of putative protease inhibitors in milk may have several roles during lactation including tissue remodelling in the mammary gland and protecting specific proteins in milk required for physiological development of the dependent young.     

Effect of Water Content on Glass Transition and Protein Aggregation of Whey Protein Powders During Short-Term Storage

The objectives of this study were to investigate the moisture-induced protein aggregation of whey protein powders and to elucidate the relationship of protein stability with respect to water content and glass transition. Three whey protein powder types were studied: whey protein isolate (WPI), whey protein hydrolysates (WPH), and beta-lactoglobulin (BLG). The water sorption isotherms were determined at 23 and 45°C, and they fit the Guggenheim–Andersson–DeBoer (GAB) model well. Glass transition was determined by differential scanning calorimeter (DSC). The heat capacity changes of WPI and BLG during glass transition were small (0.1 to 0.2 Jg⁻¹ °C⁻¹), and the glass transition temperature (T _g) could not be detected for all samples. An increase in water content in the range of 7 to 16% caused a decrease in T _g from 119 down to 75°C for WPI, and a decrease from 93 to 47°C for WPH. Protein aggregation after 2 weeks’ storage was measured by the increase in insoluble aggregates and change in soluble protein fractions. For WPI and BLG, no protein aggregation was observed over the range of 0 to 85% RH, whereas for WPH, ∼50% of proteins became insoluble after storage at 23°C and 85% RH or at 45°C and ≥73% RH, caused mainly by the formation of intermolecular disulfide bonds. This suggests that, at increased water content, a decrease in the T _g of whey protein powders results in a dramatic increase in the mobility of protein molecules, leading to protein aggregation in short-term storage.     

Characterisation of proteins in the milk of fur seals

Milk protein composition was investigated throughout the lactation periods of the Australian fur seal (Arctocephalus pusillus doriferus) and Antarctic fur seal (Arctocephalus gazella). The mean protein content of the milk was found to be 10.9% and 10.6% respectively. The concentration of total protein did not change during lactation, although a decline in casein content of the milk in late lactation was apparent. Milk protein concentration during a foraging/suckling cycle of the Antarctic fur seal analysed at the time of arrival on shore, and 24 h and 72 h after arrival was 12.8%, 11.4% and 12.5% respectively. Re-feeding animals at 72 h resulted in a significant increase in milk protein content to 14.9%. Characterisation of milk protein by SDS-PAGE analysis revealed 5 casein and 10 major whey protein bands. Amino-terminal sequencing indicated that the majority of the whey fraction of the milk is beta-lactoglobulin (beta-LG). The limited amino acid sequence indicated 3 different beta-LGs were secreted in the milk. Subsequently, RT-PCR was used to extend the sequence of one of the beta-LGs and translation of the 464 bp fragment indicated that it shared 79% sequence identity with feline beta-LG II.     

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.     

Infradian rhythmicity in milk leukocyte activity together with plasma cortisol and prolactin levels throughout the lactation period in high-yielding crossbred cows

Infradian rhythmicity in milk leukocyte activity together with plasma cortisol and prolactin levels throughout the lactation period in high-yielding crossbred cows has been studied in 10 high-yielding (milk production: 5000 l per lactation) Karan Fries crossbred (Holstein Friesian × Tharparkar) cows. Milk and blood samples were collected from all the experimental animals. Isolation of milk phagocytes (neutrophils and macrophages) and lymphocytes were done by density gradient centrifugation. In vitro phagocytic index of milk neutrophils and macrophages was performed by colorimetric NBT reductive assay. Mitogen-induced milk lymphocyte blastogenic response was estimated by colorimetric MTT (tetrazolium) assay. Total plasma cortisol and prolactin were estimated by enzyme immune assay. Highest value of plasma cortisol and prolactin was observed at calving which decreased significantly (p < 0.01) on 15th day postpartum for both prolactin and cortisol. Immune activity of milk leukocytes was highest on day 0 colostrum and decreased significantly (p < 0.01) on 7th day postpartum. A significant (p < 0.01) rise of plasma prolactin was observed around 135th and 225th days postpartum, whereas a peak level of plasma cortisol was observed at 105th, 180^th, and 270th days postpartum. Phagocytic index of milk neutrophils and macrophages remains almost in a steady state during mid-lactation period (between 100 and 200 days postpartum). A decline in increasing trend of milk phagocytic activity was observed during late lactation. Mitogen-induced milk lymphocyte blastogenic response was highest on day 0 colostrum which decreased significantly (p < 0.01) on 15th day postpartum. Con A-induced milk lymphocyte blastogenic response showed an increasing trend from 120th to 210th days postpartum. Upon correlation study, it showed that the plasma cortisol has a negative effect on milk leukocyte activity, while prolactin has a positive effect, though the effect is lactation stage specific.     

Expression of the whey acidic protein in transgenic pigs impairs mammary development

The whey acidic protein has been found in milk of mice, rats, rabbits and camels, and its gene is expressed specifically in mammary tissue at late pregnancy and throughout lactation. A characteristic of whey acidic protein is the ‘four-disulfide-core’ signature which is also present in proteins involved in organ development. We have generated six lines of transgenic pigs which carry a mouse whey acidic protein transgene and express it at high levels in their mammary glands. Transgenic sows from three lines could not produce sufficient quantities of milk to support normal development of healthy offspring. This phenotype appears to be similar, if not identical, to themilchlos phenotype exhibited by mice expressing whey acidic protein transgenes. Mammary tissue from post-partummilchlos sows had an immature histological appearance, which was distinct from that observed during normal development or involution. Expression of the whey acidic protein transgene was found in mammary tissue from sexually immature pigs frommilchlos lines, but not in sows from lines that appeared to lactate normally. We suggest that precocious synthesis of whey acidic protein impairs mammary development and function. Impaired mammary development due to inappropriate timing of whey acidic protein expression is consistent with the notion that proteins with the ‘four-disulfide-core’ signature participate in tissue formation.