Early Stages Of Lactation Research Articles

NMR-based metabolite profiling of human milk: A pilot study of methods for investigating compositional changes during lactation

Low-molecular-weight metabolites in human milk are gaining increasing interest in studies of infant nutrition. In the present study, the milk metabolome from a single mother was explored at different stages of lactation. Metabolites were extracted from sample aliquots using either methanol/water (MeOH/H2O) extraction or ultrafiltration. Nuclear magnetic resonance (NMR) spectroscopy was used for metabolite identification and quantification, and multi- and univariate statistical data analyses were used to detect changes over time of lactation. Compared to MeOH/H2O extraction, ultrafiltration more efficiently reduced the interference from lipid and protein resonances, thereby enabling the identification and quantification of 36 metabolites. The human milk metabolomes at the early (9–24 days after delivery) and late (31–87 days after delivery) stages of lactation were distinctly different according to multi- and univariate statistics. The late lactation stage was characterized by significantly elevated concentrations of lactose, choline, alanine, glutamate, and glutamine, as well as by reduced levels of citrate, phosphocholine, glycerophosphocholine, and N-acetylglucosamine. Our results indicate that there are significant compositional changes of the human milk metabolome also in different phases of the matured lactation stage. These findings complement temporal studies on the colostrum and transitional metabolome in providing a better understanding of the nutritional variations received by an infant.

Effect of functional traits on subsequent reproduction performance of Murrah buffaloes in India

ABSTRACTA study was conducted on calving records of Murrah buffaloes to study the influence of various functional traits on subsequent reproductive performance. The effects of calving abnormalities, uterine health problems, female fertility problems and udder health problem on calving to first service (CFS), service period (SP), dry period (DP) and calving interval (CI) were studied by the least-squares method using the SAS package. The increase in CFS, SP, DP and CI was 27.07%, 18.71%, 96.74% and 6.70%, respectively. Subsequently, the average milk yield per day of calving interval was found to be reduced (from 4.91 to 2.10 kg/day) in these animals in comparison with the normal calvers. A highly significant increase in average CFS, SP, DP and CI was found among animals susceptible to metritis (16.93%, 73.88%, 53.92% and 20.04%, respectively). The decrease in average milk yield per day of calving interval (MY/CI) was 18.55% in comparison with the animals not affected by metritis. The average MY/CI was observed to be 16.47% lower in the anoestrus-affected animals in comparison with normal animals. The increase in average SP, DP and CI associated with repeat breeding cases was 162.63%, 87.58% and 50.15%, respectively. The increase in average DP and CI due to incidence of mastitis was 10.48% and 4.26%, respectively. The increase in average dry period associated with the incidence of mastitis during early stage of lactation (1–60 days) was 13.63%. The incidence of mastitis during early stage of lactation significantly reduced the average MY/CI by 5.50 and 14.20%, respectively.

Models for Estimating Genetic Parameters of Milk Production Traits Using Random Regression Models in Korean Holstein Cattle.

The objectives of the study were to estimate genetic parameters for milk production traits of Holstein cattle using random regression models (RRMs), and to compare the goodness of fit of various RRMs with homogeneous and heterogeneous residual variances. A total of 126,980 test-day milk production records of the first parity Holstein cows between 2007 and 2014 from the Dairy Cattle Improvement Center of National Agricultural Cooperative Federation in South Korea were used. These records included milk yield (MILK), fat yield (FAT), protein yield (PROT), and solids-not-fat yield (SNF). The statistical models included random effects of genetic and permanent environments using Legendre polynomials (LP) of the third to fifth order (L3–L5), fixed effects of herd-test day, year-season at calving, and a fixed regression for the test-day record (third to fifth order). The residual variances in the models were either homogeneous (HOM) or heterogeneous (15 classes, HET15; 60 classes, HET60). A total of nine models (3 orders of polynomials×3 types of residual variance) including L3-HOM, L3-HET15, L3-HET60, L4-HOM, L4-HET15, L4-HET60, L5-HOM, L5-HET15, and L5-HET60 were compared using Akaike information criteria (AIC) and/or Schwarz Bayesian information criteria (BIC) statistics to identify the model(s) of best fit for their respective traits. The lowest BIC value was observed for the models L5-HET15 (MILK; PROT; SNF) and L4-HET15 (FAT), which fit the best. In general, the BIC values of HET15 models for a particular polynomial order was lower than that of the HET60 model in most cases. This implies that the orders of LP and types of residual variances affect the goodness of models. Also, the heterogeneity of residual variances should be considered for the test-day analysis. The heritability estimates of from the best fitted models ranged from 0.08 to 0.15 for MILK, 0.06 to 0.14 for FAT, 0.08 to 0.12 for PROT, and 0.07 to 0.13 for SNF according to days in milk of first lactation. Genetic variances for studied traits tended to decrease during the earlier stages of lactation, which were followed by increases in the middle and decreases further at the end of lactation. With regards to the fitness of the models and the differential genetic parameters across the lactation stages, we could estimate genetic parameters more accurately from RRMs than from lactation models. Therefore, we suggest using RRMs in place of lactation models to make national dairy cattle genetic evaluations for milk production traits in Korea.

Incidence of resistant mastitis in dairy cows in Tamil Nadu, India

The incidence of resistant mastitis in dairy cows in Tamil Nadu, India was 56.l %. The predominant resistant causative pathogen was Escherichia coli (50.64 %) followed by Staphylococcus aureus (44.25 %) and Methicillin resistant Staphylococcus aureus (5.11 %). Incidence of resistant mastitis was high in Holstein Friesian cross breed followed by Jersey cross breed and non descript. Highest incidence was observed in early stage of third lactation. In vitro antibiotic sensitivity test revealed the E. coli, S. aureus and MRSA organisms showed more sensitivity to enrofloxacin, amoxicillin+sulbactam, gentamicin and ceftriaxone and had highest resistant to penicillin followed by amoxicillin, oxytetracycline and methicillin. The study highlights the need for preventing the indiscriminate use of antibiotics.

Assessment of lactation stage and breed effect on sheep milk fatty acid profile and lipid quality indices

Information on fatty acid (FA) profile is critical for the production and promotion of sheep milk and derivative dairy products. The presence of the essential ω-3 and ω-6 FA in milk fat as well as other less common FA, like linoleic acid isomers, has gained an increasing interest due to the consumer demand for a healthy diet. This research assesses the FA profile and estimates the lipid quality indices (ratio between hypocholesterolaemic and hypercholesterolaemic fatty acids, peroxidisability index, atherogenic index, and thrombogenic index) of raw milk and cream fat from two indigenous Greek sheep breeds (Karagouniko and Chios) at different lactation stages. Raw milk and cream fat presented a favorable ω-6/ω-3 ratio below 4:1. Atherogenic and thrombogenic indices of all studied milk fat fluctuated in sufficiently low levels (<3). The FA profile and lipid quality indices in both raw milk and cream samples differed significantly depending more on the lactation stage compared to the breed type. Raw milk fat from late lactation had more beneficial fatty acid profile compared to early and middle lactation stages. Differences among breeds were highlighted when raw milk and cream samples were compared within the same lactation stage. Raw milk and cream fat from Karagouniko breed were characterised by higher ω-3 proportion, lower ω-6/ω-3 ratio and lower thrombogenic index value compared to those from Chios breed.

PREVALENCE OF BUFFALO MASTITIS IN Mastitis in Buffalo in DAKAHLIA Dakahyllia GOVERNORATEs

This study surveyed the mastitis prevalence and risk factors in buffalo’s population in Dakahlia Governorate. A total of 471 Water buffaloes (Bubalus bubalis) brought to the Veterinary Teaching Hospital, Mansoura, Dakahlia Governorates from 2009 to 2012 were analyzed to determine, the seasonal occurrence of mastitis, prevalence in relation to the lactation stage. Isolation and identification of causative agent using PCR and other serological technique were applied. The prevalence of buffalo's mastitis was 19.9% and 5.9% for clinical and subclinical mastitis respectively. A high incidence of clinical mastitis (51.6%) was observed in animal during their early lactation stage, while high incidences of subclinical mastitis recorded (12.9%) in late lactation stage. And the most isolated microorganism is E-coli spp. The Statistical analysis of our results revealed that a significant variance between the occurrence of mastitis and lactation season, P< 0.001.

Estimation of the growth curve and heritability of the growth rate for giant panda (Ailuropoda melanoleuca) cubs.

Giant panda cubs have a low survival rate during the newborn and early growth stages. However, the growth and developmental parameters of giant panda cubs during the early lactation stage (from birth to 6 months) are not well known. We examined the growth and development of giant panda cubs by the Chapman growth curve model and estimated the heritability of the maximum growth rate at the early lactation stage. We found that 83 giant panda cubs reached their maximum growth rate at approximately 75-120 days after birth. The body weight of cubs at 75 days was 4285.99 g. Furthermore, we estimated that the heritability of the maximum growth rate was moderate (h(2) = 0.38). Our study describes the growth and development of giant panda cubs at the early lactation stage and provides valuable growth benchmarks. We anticipate that our results will be a starting point for more detailed research on increasing the survival rate of giant panda cubs. Feeding programs for giant panda cubs need further improvement.

An opportunity to revolutionise sow management

Research in any area of animal production can provide the opportunity to change how the system operates and is managed. The reliance on having to wean lactating sows to re-mate them has limited the commercial options for sow management. The desire to limit lactation length to maximise the litters per sow per year concurrently creates major challenges for such-aged piglets weaned abruptly. These issues are discussed in the review. This management system also fails to recognise that sows have the potential to spontaneously ovulate in lactation even when housed in farrowing crates. Inhibition of luteinising hormone release is the basis of lactational anoestrus with the suckling stimulus providing the strongest afferent signal to this inhibitory system. Any management strategy that reduces this inhibition has the potential to trigger lactational oestrus. In this review, group housing of sows, boar exposure and intermittent suckling are identified as strong stimuli that can promote lactational oestrus. Removing the need to wean sows to mate them offers further opportunities to change the way lactating sows are managed. One option is a two-stage lactation system in which the sows are housed in farrowing crates for the first 10–14 days and then moved to group accommodation for the remainder of lactation. This system provides welfare benefits for the litter in the early stage of lactation and then the benefits of less confinement for the sows in later lactation. Group lactation would also lend itself to the implementation of stimuli to assist the mating of sows in lactation, such as piglet separation and/or boar exposure. It also accommodates the mating of sows that spontaneously ovulate in lactation. Removing the need to wean sows to re-mate them provides the opportunity to increase weaning age and implement a gradual weaning, helping to attenuate the post-weaning growth check and potentially limiting antimicrobial use in weaner pigs.

Identification of conserved microRNAs in peripheral blood from giant panda: expression of mammary gland-related microRNAs during late pregnancy and early lactation.

The giant panda (Ailuropoda melanoleuca) is one of the world's most endangered mammals, and it has evolved several unusual biological and behavioral traits. During puberty, pregnancy, lactation, and involution, the mammary gland undergoes profound morphological and functional changes. A large number of microRNAs (miRNAs) have been identified to be involved in mammary gland development and lactation. In this study, we identified 202 conserved mature miRNAs, corresponding to 147 pre-miRNAs, in giant panda peripheral blood using a small RNA-sequencing approach. In addition, 27 miRNA families and 29 miRNA clusters were identified. We analyzed the arm selection preference of pre-miRNAs and found that: 1) most giant panda pre-miRNAs generated one-strand miRNAs, and the 5p-arm only miRNAs have a higher expression level than 3p-arm only miRNAs; 2) there were more 5p-arm dominant miRNAs than 3p-arm dominant miRNAs; and 3) 5p-arm dominant miRNAs have a larger fold change within miRNA pairs than 3p-arm dominant miRNAs. Expression of 12 lactation-related miRNAs was detected across late pregnancy and early lactation stages by qPCR, and seven miRNAs were identified as clustered in one significant model. Most of these clustered miRNAs exhibited inhibitory roles in proliferation and differentiation of mammary epithelial cells. Functional analysis highlighted important roles of the seven as signed miRNAs in mammary development and metabolic changes, including blood vessel morphogenesis, macromolecule biosynthesis, cell cycle regulation, and protein transport.

Effects of Pregnancy and Lactation on Iron Metabolism in Rats.

In female, inadequate iron supply is a highly prevalent problem that often leads to iron-deficiency anemia. This study aimed to understand the effects of pregnancy and lactation on iron metabolism. Rats with different days of gestation and lactation were used to determine the variations in iron stores and serum iron level and the changes in expression of iron metabolism-related proteins, including ferritin, ferroportin 1 (FPN1), ceruloplasmin (Cp), divalent metal transporter 1 (DMT1), transferrin receptor 1 (TfR1), and the major iron-regulatory molecule—hepcidin. We found that iron stores decline dramatically at late-pregnancy period, and the low iron store status persists throughout the lactation period. The significantly increased FPN1 level in small intestine facilitates digestive iron absorption, which maintains the serum iron concentration at a near-normal level to meet the increase of iron requirements. Moreover, a significant decrease of hepcidin expression is observed during late-pregnancy and early-lactation stages, suggesting the important regulatory role that hepcidin plays in iron metabolism during pregnancy and lactation. These results are fundamental to the understanding of iron homeostasis during pregnancy and lactation and may provide experimental bases for future studies to identify key molecules expressed during these special periods that regulate the expression of hepcidin, to eventually improve the iron-deficiency status.

Milk Urea Nitrogen of Healthy and Repeat Breeder Buffaloes Reared under Two Different Feeding Systems

Milk urea nitrogen (MUN) measurement is a convenient and non-invasive method to assess the protein and energy nutrition of dairy cattle. The present study was taken up with 36 lactating buffaloes maintained under two different feeding systems i.e. 18 each from intensive (dairy farm) or semi-intensive (on-farm, field) conditions to study the effect of production, managemental and nutritional variables on baseline MUN. Milk sample were collected from both systems for 8 weeks from 6 buffaloes each in early (0–45), mid (46–150) and late (>150 days in milk) stages of lactation. The milk samples were collected on alternate days i.e. from morning milking on 1st and 5th day and from evening milking on 3rd and 7th day. Additionally, MUN was estimated for 7d from 6 animals with history of repeat breeding in each system. The system wise nutrient profile of feedstuffs, animal performance data along with environmental profile were fed into CNCPS version 5.0 to evaluate the diets and to formulate optimized diets for repeat breeding animals. Subsequently, the effect of feeding such diets on MUN levels and post AI conception was studied. The baseline MUN levels were influenced by production, nutritional and managemental variables. The average baseline MUN (mg/dl) vs. the MUN in repeat breeding buffaloes (P 0.05). The feeding of optimized (using CNCPS version 5.0) rations resulted in a significant (P<0.05) decrease in the MUN (mg/dl) in repeat breeding farm (10.73±0.27) and field (8.12±0.24) buffaloes and four out of six farm buffaloes and two out of six field buffaloes have conceived after feeding the test diet. It is concluded that MUN can be employed as a potential tool to evaluate protein nutrition of dairy buffaloes.

Expression Analysis of Solute Carrier (SLC2A) Genes in Milk Derived Mammary Epithelial Cells during Different Stages of Lactation in Sahiwal (Bos indicus) Cows

Solute carriers (SLC2A/ GLUT) are one of the major types of transporter superfamily that have been predominantly involved in active transport of glucose across the plasma membrane. Glucose uptake by mammary epithelial cells (MECs) is an important step in the milk synthesis during lactation, and hence directly influences the milk yield. Use of MEC isolated from milk has been speculated to be a good alternative to mammary gland tissues in order to understand the expression profile of important genes associated with lactation, in particular large dairy animals where obtaining biopsies is sometimes difficult. The present study was therefore undertaken in milk purified MECs to assess relative mRNA expression of major solute carriers/glucose transporters (SLC2A/GLUTs) viz., SLC2A1(GLUT1), SLC2A(GLUT4), SLC2A8(GLUT8), SLC2A12(GLUT12) and hexokinase (HK2) genes during; early(10-20 days), peak (30-50 days), mid (100-140 days) and late (215-245 days) lactation stages of Sahiwal cows. MECs were isolated from fresh milk, using Dyna Beads coated with anticytokeratin 18 antibodies. For normalization of qPCR expression data, 10 known housekeeping genes (HKGs) from different functional classes were evaluated. A panel of four best stable HKGs; eukaryotic translation elongation factor 1 alpha (EEF1A1), ribosomal protein L4(RPL4), glyceraldehyde-3-phosphate dehydrogenase (GAPDH), actin-beta (ACTB) were identified through ge Norm, Norm Finder and Best Keeper analysis. Expression level of SLC2A1 was significantly (P<0.05) higher during peak/mid lactation period as compared to late lactation period. Similarly, SLC2A8 mRNA expression was relatively higher during mid-lactation stages than other stages of lactation. In contrast, SLC2A4 expression level was relatively higher during the late lactation stages. The SLC2A12 mRNA on the other hand was undetectable, indicating its expression to be either very low or absent in MEC of Sahiwal cows. Our expression data indicated SLC2A1, SLC2A4 and SLC2A8 to be the major solute carriers in Sahiwal MEC. Further, HK2 expression was significantly (P<0.05) higher during early and mid-lactation stages. The stage specific expression about of major SLC2A/GLUT and HK2 genes indicate their functional role in regulating glucose uptake in MECs of Sahiwal cows.

Genetic analysis of milk β-hydroxybutyrate and its association with fat-to-protein ratio, body condition score, clinical ketosis, and displaced abomasum in early first lactation of Canadian Holsteins

The aim of this study was to estimate genetic parameters for milk β-hydroxybutyrate (BHBA) in early first lactation of Canadian Holstein cows and to examine its genetic association with indicators of energy balance (fat-to-protein ratio and body condition score) and metabolic diseases (clinical ketosis and displaced abomasum). Data for milk BHBA recorded between 5 and 100 d in milk was obtained from Valacta (Sainte-Anne-de-Bellevue, Québec, Canada), the Canadian Dairy Herd Improvement organization responsible for Québec and Atlantic provinces. Test-day milk samples were analyzed by mid-infrared spectrometry using previously developed calibration equations for milk BHBA. Test-day records of fat-to-protein ratio were obtained from the routine milk recording scheme. Body condition score records were available from the routine type classification system. Data on clinical ketosis and displaced abomasum recorded by producers were available from the national dairy cattle health system in Canada. Data were analyzed using linear animal models. Heritability estimates for milk BHBA at different stages of early lactation were between 0.14 and 0.29. Genetic correlations between milk BHBA were higher between adjacent lactation intervals and decreased as intervals were further apart. Correlations between breeding values for milk BHBA and routinely evaluated traits revealed that selection for lower milk BHBA in early lactation would lead to an improvement of several health and fertility traits, including SCS, calving to first service, number of services, first service to conception, and days open. Also, lower milk BHBA was associated with a longer herd life, better conformation, and better feet and legs. A higher genetic merit for milk yield was associated with higher milk BHBA, and, therefore, a greater susceptibility to hyperketonemia. Milk BHBA at the first test-day was moderately genetically correlated with fat-to-protein ratio (0.49), body condition score (−0.35), and clinical ketosis (0.48), whereas the genetic correlation with displaced abomasum was near zero (0.07). Milk BHBA can be routinely analyzed in milk samples at test days, and, therefore, provides a practical tool for breeding cows less susceptible to hyperketonemia.

Effect of ration balancing on methane emission, faecal archaeol concentration and its relation to enteric methane in crossbred cows

A field study was conducted to evaluate the effect of ration balancing on methane emission, faecal archaeol and its relation with enteric methane in crossbred cows. Crossbred cows (25) in their early stage of lactation (60–80 d postpartum) were identified under field conditions. After recording their average daily feed intake and milk yield for 1 week, methane emission was measured by SF6 tracer technique. A balanced ration was worked out for individual cows and fed to them for 30 d. After feeding a balanced ration, feed intake and methane emission was measured again. On feeding a balanced ration, methane emission (g/d) was reduced by 10.1%. Archaeol concentration in faeces being considered as an indicator of methane emission, its concentration in faeces was measured before and after feeding a balanced ration, which reduced significantly. There existed a significant correlation (r=0.12) between methane emission measured by SF6 tracer technique (g/d) and archaeol concentration (mg/kg DM of faeces). However, more data need to be generated in this regard.

Differential regulation of GLUT1 and GLUT8 expression by hypoxia in mammary epithelial cells.

Glucose is a major substrate for milk synthesis and is taken up from the blood by mammary epithelial cells (MECs) through facilitative glucose transporters (GLUTs). The expression levels of GLUT1 and GLUT8 are upregulated dramatically in the mammary gland from late pregnancy through early lactation stages. This study aimed to test the hypothesis that this increase in GLUT1 and GLUT8 expression involves hypoxia signaling through hypoxia inducible factor-1α (HIF-1α) in MECs. Mouse mammary glands showed significantly more hypoxia in midpregnancy through early lactation stages compared with in the virgin stage, as stained by the hypoxia marker pimonidazole HCl. Treatment with hypoxia (2% O2) significantly stimulated glucose uptake and GLUT1 mRNA and protein expression, but decreased GLUT8 mRNA expression in bovine MECs. In MECs, hypoxia also increased the levels of HIF-1α protein in the nuclei, and siRNA against HIF-1α completely abolished the hypoxia-induced upregulation of GLUT1, while having no effect on GLUT8 expression. A 5'-RCGTG-3' core HIF-1α binding sequence was identified 3.7 kb upstream of the bovine GLUT1 gene, and HIF-1α binding to this site was increased during hypoxia. In conclusion, the mammary glands in pregnant and lactating animals are hypoxic, and MECs respond to this hypoxia by increasing GLUT1 expression and glucose uptake through a HIF-1α-dependent mechanism. GLUT8 expression, however, is negatively regulated by hypoxia through a HIF-1α-independent pathway. The regulation of glucose transporters through hypoxia-mediated gene transcription in the mammary gland may provide an important physiological mechanism for MECs to meet the metabolic demands of mammary development and lactation.

Donor milk volume and characteristics of donors and their children

BackgroundLittle is known regarding the effect of the characteristics of donors and their children on the volume of donor milk delivered to a human milk bank (HMB). AimsOur study aimed to determine the relationship between different social and demographic variables of donors and their infants with the volume of human milk delivered. MethodsWe included donors accepted at the Hospital Doce de Octubre HMB from January 1st, 2009 until April 31st, 2013, and who had finished their donation. Data of social and demographic characteristics of the donors and their children, and the total volume of DHM given were obtained from our HMB database. Included variables were previous donors, donor age, number of children, place of residence, gestational age of the infant at birth, child's age at the start of the donation, hospital admission, and death of the infant.A linear regression model was used to study the relationship between independent variables that were significant in bivariate analysis and the volume of donated milk. ResultsA total of 415 donations from 391 women were included. The median volume of milk delivered was 3.1l (IQR—interquartile range—1.3–8.3l). In the linear regression model, previous donors, smaller gestational age of children, and the start of donation at earlier stages of lactation were associated with a larger quantity of HMB donated (p≤0.001). ConclusionPrevious donors, smaller gestational age of children, and the start of donation at earlier stages of lactation are associated with a larger quantity of milk donated to the HMB.

Impact of husbandry, stages of lactation and parity number on milk yield and chemical composition of dromedary camel milk

The present study was designed to assess the impact of husbandry, stage of lactation and parity number on milk yield and chemical composition of camel milk within three different camel farms at Khartoum State, Sudan. Camel milk samples (n=220) were collected from 43 healthy she-camels at different lactation stages (early, mid, late and latest stages of lactation) and parity number (1-7 parities). The overall means of daily milk yield and composition of fat, protein, lactose, solids not fat (SNF), acidity and density were 2.73±1.16 L/day, 3.69±1.31%, 3.32±0.33%, 4.59±0.45, 8.49±0.86%, 0.19±0.03% and 1.030±0.017g/cm3, respectively. Camel milk yield and composition were significantly (P<0.05) affected by husbandry, stage of lactation and parity number. The highest milk yield (3.49±0.89 L/day) was recorded for she-camels kept in the intensive farming system during early stage of lactation (2.96±1.28 L/day). The result showed that the she-camels in the second parity gave the highest milk yield (4.06±1.85 L/day), while the lower milk yield was found at the subsequent parities. The highest means of fat (4.05±1.5%), SNF (8.78±0.74%), protein (3.41±0.3%) and lactose (4.67±0.42%) were recorded for the milk of she camels in the semi-intensive farming. The highest means of fat, protein, lactose and SNF (4.46±1.62%, 3.5±0.27%, 4.75±0.42% and 8.88±0.89%, respectively) were found in camel milk during the early stage of lactation. Moreover the highest means of protein, lactose and SNF (3.42±0.33%, 4.71±0.52% and 8.83±0.86%, respectively) were recorded in milk for the she camels at parity number five. This study concluded that husbandry systems, stage of lactation and parity number have impact on milk yield and chemical composition of camel milk. Therefore, factors that cause variations in milk yield and composition should be considered for the nutritional and technological uses of camel milk.

Effects of Abortion and Stage of Lactation on Chemical Composition and Mineral Content of Goat Milk from Mixed-breed Goat on Rangeland

The objective of this study was to analyze the chemical and mineral composition of aborted goats as well as goats with normal kidding for an entire lactation (five months; rainy season under range conditions), and the effect of stage of lactation on various raw milk components. Thirty one multiparous goats of mixed-breed goats were used, 16 carried their pregnancy to term and 15 aborted about the fourth month of pregnancy. Percentage of milk fat fluctuated greatly (P<0.01) throughout lactation with no differences between aborted and non-aborted goats (5.0 vs. 4.8g/100g). Percentage protein was higher (P<0.05) in aborted goats compared to non-aborted goats (4.7 vs. 4.5g/100g). During the early stage of lactation, milk contained higher (P<0.01) lactose levels which then decreased gradually towards the end of lactation. No difference in this milk component was detected between groups of goats (4.6 vs. 4.5g/100g). Both magnesium and manganese in goat milk were higher in aborted than non-aborted goats. It was concluded that some milk components are increased in milk from goats whose lactation initiate with abortion, compared with milk from goats whose lactation derive from normal kidding.

Genetic correlations between production and disease traits during first lactation in Holstein cows

The aim of this study was to estimate genetic correlations between milk yield, somatic cell score (SCS), mastitis, and claw and leg disorders (CLDs) during first lactation in Holstein cows by using a threshold–linear random regression test-day model. We used daily records of milk, fat and protein yields; somatic cell count (SCC); and mastitis and CLD incidences from 46 771 first-lactation Holstein cows in Hokkaido, Japan, that calved between 2000 and 2009. A threshold animal model for binary records (mastitis and CLDs) and linear animal model for yield traits were applied in our multiple trait analysis. For both liabilities and yield traits, additive genetic effects were used as random regression on cubic Legendre polynomials of days on milk. The highest positive genetic correlations between yields and disease incidences (0.36 for milk and mastitis, 0.56 for fat and mastitis, 0.24 for protein and mastitis, 0.32 for milk and CLD, 0.44 for fat and CLD and 0.31 for protein and CLD) were estimated at about the time of peak milk yield (36 to 65 days in milk). Selection focused on early lactation yield may therefore increase the risk of mastitis and CLDs. The positive genetic correlations of SCS with mastitis or CLD incidence imply that selection to reduce SCS in the early stages of lactation would decrease the incidence of both mastitis and CLD.

CERULOPLASMIN ACTIVITY AND ITS RELATION TO COPPER LEVEL IN BLOOD SERUM OF FRIESIAN DAIRY COWS.

The relationship between ceruloplasmin, a metalloenzyme with oxidase activity, and copper was investigated in Frisian dairy cows.The oxidase activity of ceruloplasmin correlated closely with the serum copper concentrations in Frisian dairy cows. Variations of copper (Cu) concentration and ceruloplasmin (Cp) activity in serum of dairy cows at different stages of lactation were assessed in 60 Frisian dairy cows. Furthermore, ceruloplasmin to copper ratios were also investigated. The cows were classified according to their lactation stages into three different groups as early lactation stage (4–6 weeks postpartum), mid-lactation stage (17–22 weeks postpartum) and late-lactation stage (25-30 weeks post-partum). Each group consisted of 20 multiparous cows. Serum samples were obtained from each cow for estimation of cereloplasmin activity and copper levels. Concentrations of serum copper (sCu) were higher in the group of early lactation stage than the other groups (P < 0.05). Serum cereloplasmin (sCp) activity also showed significant difference between early lactation, mid and late lactation groups (P < 0.05). The ratios of cereloplasmin activity to copper concentration (Cp/Cu) were significantly changed in the different lactation stages of dairy cows (P< 0.05). For evaluation of copper status, use of sCp/sCu identified more animals as ‘low’ and ‘marginal’. It can be concluded that ceruloplasmin and copper undergo a physiological increase justafter calving; thus, their values should be interpreted with caution during assessment of copper status. Further research is required to refine diagnosis criteria for use of such ratio in determining copper status in Frisian dairy cows.