Short Lactation Research Articles

Changes of muscle fibre profile and fat cell size around first parturition in cows differing in lactation performance

The presented study investigated changes of fat cell and muscle fibre size, and muscle fibre type composition around first parturition in cows with a combined beef and dairy genetic background. In contrast to high-merit dairy cows, these cows can serve as a model for beef cows because of the very low milk production level. Fifty heifers used in this experiment were F2 offspring originating from mating Charolais bulls to German Holstein cows and a following intercross of F1 individuals. They were assigned to 3 groups according to their lactation performance, namely high lactating (HL), low lactating long (LLL; duration of first lactation at least 100 days), and low lactation short (LLS; duration of first lactation shorter than 100 days). Biopsy samples were taken from semitendinosus muscle (MST) and subcutaneous fat (SCF) at three time points, 10 days before first parturition, 30 and 100 days after calving. These samples were investigated by histology and computer image analysis for muscle fibre profile, as well as intramuscular and subcutaneous fat cell size to estimate the impact of lactation on body reserves. Most cows continued growth and gained weight during lactation. Continuous tissue accretion was indicated on the cellular level by an increase in intramuscular fat cell size. Subcutaneous fat cells were larger in low lactating cows with a short lactation period. There were no morphological signs of fat mobilization from fat cells. There was also no protein mobilization indicated by changes in muscle fibre size. However, the increase in percentage of fast, glycolytic muscle fibres indicated alterations in muscle metabolism during transition from late pregnancy to early lactation. Cows remained obviously in a positive energy balance in this study and continued tissue accretion during lactation. This was reflected on the cellular level in skeletal muscle and subcutaneous fat.

Comparative expression profiling of insulin-like growth factor binding protein-5 in milk of Bos indicus and Bubalus bubalis during lactation

Insulin-like growth factor binding protein-5 (IGFBP-5) is a key molecule in mammary gland development, which facilitates the removal of mammary epithelial cells (MECs) by apoptosis that takes place during remodeling of the mammary gland during involution. IGFBP-5 binds with IGFs for their bioavailability. IGFBP-5 has been reported to perform pleiotropic roles such as cellular apoptosis, proliferation and differentiation. To understand the role of IGFBP-5 during lactation and clinical mastitis, expression profiling of IGFBP-5 at the protein level was performed in both indigenous cows (Bos indicus) and buffaloes (Bubalus bubalis) belonging to two different breeds – Sahiwal cows and Murrah buffaloes. Reverse-transcriptase PCR (RT-PCR) of IGFBP-5 mRNA confirmed its expression in milk somatic cells and MECs of Sahiwal cows. ELISA was performed for quantitative measurement of IGFBP-5 concentrations in milk during different days (0, 50, 100, 150, 200, 250 and 300) of lactation, during the involution period and in animals exhibiting short lactation and clinical mastitis. The highest concentration of IGFBP-5 in milk was observed during the involution period followed by colostrum, late and early lactation, respectively, in both cattle and buffaloes. No significant difference in the concentration of IGFBP-5 was observed during the first 150 days of lactation between cows and buffaloes. However, higher concentration of IGFBP-5 was observed in cows during late lactation (200 to 300 days) in comparison with buffaloes. To validate the ELISA data, quantitative real-time PCR was performed in MECs of Sahiwal cows. The relative mRNA abundance of IGFBP-5 was found to be significantly (P<0.05) higher on day 15 than between 50 and 150 days of lactation in case of Sahiwal cows. Highest mRNA expression of IGFBP-5 was observed around 300 days of lactation followed by 200 and 250 days (P<0.05), respectively. Murrah buffaloes showed low levels of IGFBP-5 protein in milk as compared with Sahiwal cows during lactation in ELISA. Animals having history of short lactation length (short lactating animals) showed higher levels of IGFBP-5 expression (at protein level) in comparison with normal lactating animals. We propose that higher level IGFBP-5 expression may have functional significance in lactation persistency. As a pro-apoptotic molecule, higher expression of IGFBP-5 was observed to be inversely related to lactation length and milk production.

Effects of lactation length and boar contact in early lactation on expression of oestrus in multiparous sows

The ability to stimulate a fertile oestrus during early lactation provides an opportunity to increase piglet weaning age whilst maintaining 2.4litters per sow per year. This study evaluated the effects of boar contact beginning on day 7 of lactation and lactation length on lactation oestrus induction and subsequent reproductive output in multiparous sows (parity 2.9±0.16; mean±SEM; range 2–6). Large White×Landrace multiparous sows were allocated to one of four treatment groups; weaning at 26 days post-partum and no boar contact (control); weaning at 26 days and boar contact (BC); weaning at 7 days and boar contact (BC+short lactation (SL)); and weaning at 7 days and no boar contact (SL). Control and SL sows were taken for a short walk daily during which a backpressure test was performed in the absence of a boar. Oestrus expression within 26 days of farrowing was significantly higher in BC (67%) and BC+SL (93%) sows than control (11%) and SL (13%) sows (P<0.05). Of sows mated within 26 days of farrowing, there was no difference in the number of piglets born alive or stillborn. Therefore, boar contact is an effective method to stimulate oestrus within 26 days of farrowing in both lactating and weaned sows.

Application of the Wood lactation curve in analysing the variation of daily milk yield in the Zaraibi goats in Egypt

Test-day records (55,161 in total) collected over the period 1995–2008 from 31,762 lactations of 2202 does raised at an experimental station were used to estimate the lactation curve for Egyptian Zaraibi goats. Milk yield was recorded every 2 weeks, including the suckling period. Daily records from does with at least 6 weeks of lactation including low milk yield or short lactations were used. The Wood function was fitted to the milk records with the parameters associated with initial daily yield (a), rate of increase prior to the peak yield (b) and rate of decrease after it (c). The analyses were done only for 1553 lactations from 944 does with positive curve parameters. The Wood function-based estimates (standard deviation) were: peak week (PW) 3.64 weeks (3.28); peak milk yield (PMY) 1.92kg (0.70); and persistency (S) 1.38 (0.37). Total milk yield (TMY) computed from the daily records had a mean of 253kg (standard deviation (SD)=59.9). Genetic variation in all studied traits was analysed using the average information-restricted maximum likelihood (AI-REML) algorithm. The fixed effects considered were parity, year and season of kidding and litter size at kidding. Heritability estimates for the function parameters were low (0.023–0.044). Positive genetic correlation (0.23) was found between PW and PMY while the phenotypic correlation was negative (−0.33). Selection for high initial daily yield may lead to high production, delayed peak, reasonable persistency and high TMY. With the found correlations, selection on PMY would be less effective for increasing TMY than direct selection. Despite the high average number (about 15) of test-day records per lactation, a high proportion of atypical curve parameters was found and the heritability and correlation estimates were low and with relatively high standard errors. The estimate of PW and the related curve parameters had high standard errors. More attention should be paid to the accuracy in measuring milk yield and to starting milk yield recording immediately after kidding to arrive at better estimates for the shape of the lactation curve.

Factors affecting the lactation curves of intensively managed sheep based on a clustering approach

This study investigated factors affecting milk production and lactation curves from complete lactations of Lacaune dairy sheep. Animals were part of a single flock under intensive management and were milked twice daily starting at lambing. The results of the analyses of 7788 complete lactations showed an average total milk yield of 434±183l from lactations 234±63d long, with an average lambing interval of 302±65d. A Pollott additive mathematical model was used to estimate complete lactation curves. Clustering analysis identified four lactation types among Lacaune dairy sheep differing mainly in productivity i.e. milk yield per lactation (MY) and length of lactation (DIM). The so-called SL type involved short, less productive lactations (n=2137; 27·4%; MY=222±75·5l and DIM=182±52·9d). The SN type involved short lactations of normal productivity (n=2039; 26·2%; MY=396±73·7l and DIM=205±33·1d). The LP type involved long and productive lactations (n=2169; 27·9%; MY=487±70·5l and DIM=265±40·7d), while the LVP type included long and extremely productive lactations (n=1443; 18·5%; MY=694±114·0l and DIM=295±54·7d). Sheep showing the best lactation curves were usually younger than other sheep, and they had higher yield during the previous lactation, a shorter previous dry period (55±50·4 for LP and 61±55·0d for LVP types) and longer lambing intervals. In addition, they tended to be born in September and to lamb in March, October and December. Sheep were remarkably stable in their lactation curve behaviour: the curve type observed for the first lactation was highly likely to persist in subsequent lactations (P<0·0001). These results suggest that farmers can use the shape of the first lactation curve to guide their selection of ewes for breeding and retention on the farm, thereby improving flock productivity.

A Qualitative Study of Risk Factors Related to Child Malnutrition in Aileu District, Timor-Leste

Improvement in child nutritional status is one of the major health priorities in Timor-Leste. A qualitative study was conducted in Aileu District, adjacent to the capital of Timor-Leste, Dili, in September 2010 to determine the possible risk factors associated with the high prevalence of child malnutrition. In-depth interviews were conducted to 32 guardians of children aged younger than 5 years. It was observed that early termination of exclusive breast-feeding and a short lactation period along with an unsanitary living environment were associated with the nutritional status of children in the study area. Although previous surveys have reported poor food security conditions in the country, no statements from the subjects supported this contention. The identified possible risk factors for child malnutrition were closely linked to each other and were mostly modifiable.

WPŁYW DŁUGOŚCI OKRESU ZASUSZENIA KRÓW PIERWIASTEK I STARSZYCH NA ICH UŻYTKOWOŚĆ W KOLEJNYM CYKLU PRODUKCYJNYM

Analysis was made of the effect of dry period length in first-calf heifers and older cows from the active population of cows in the Pomerania and Kujavia regions on their performance in the next production cycle. The GLM, FREQ and CORR PEARSON procedures of the SAS package were used for statistical calculations. It was found that a dry period of 41-60 days is the most favourable in terms of next lactation milk yield. Any shortening of the dry period, especially to less than 20 days, is particularly inadvisable for first-calf heifers. Dry periods of 21-40 days are the most favourable considering survival of cows (especially the oldest cows) in the next production cycle. Extending the standard dry period of 41-60 days by 20 days causes a slight decrease in performance (as determined by the parameters mentioned above) but extending it by another 20 days is highly detrimental. Especially in the oldest cows, a dry period that is too long (over 100 days) may carry the risk of increased culling in the herd, shorter lactations and poorer reproductive performance.

Predicting lactation yields in dairy buffaloes by interpolation and multiple trait prediction

Milk recording systems for dairy buffaloes in the Philippines suffer from missing or irregular fat and protein test intervals; hence a suitable method to predict lactation yield is needed. The test interval method was compared with methods that incorporate information on standard lactation curves using Wilmink's (Wil) or Wood's (Wood) function. The latter two methods were also evaluated using a multiple trait procedure with covariances between milk, fat and protein yields, MTP-Wil and MTP-Wood, for 305D yield prediction. For this purpose, 1700 lactation records of dairy buffaloes from seven herds located in the north and south of the Philippines were used. All lactations have daily milk yields and most also have monthly fat and protein test day yields. Accuracy of predicting 305D milk, fat and protein yields were evaluated using ≥9 test day yields (≥9TD) of complete lactations, part lactation of varying lengths and lactations with missing tests with varying intervals between tests. The five methods were compared based on mean squared error and correlation between the predicted and true 305D yield. Prediction of 305D milk and protein yields was equally precise among the five methods when ≥9 test day yields were used. In general, MTP-Wil had slightly better precision compared with TIM and Wil methods in extending part lactations to 305D yields for all 3 traits. The use of Wood's function to model the lactation curve resulted in large prediction error when extending yields to 305D from short lactations. The methods, MTP-Wil and MTP-Wood, which utilize information on covariances between traits had slightly better performance and are able to handle missing tests and longer intervals between tests better than other methods. Fat and protein 305D yields can be predicted using a single test with almost similar accuracy using ≥9TD yields provided that complete milk test day information is available. Overall, MTP-Wil performed better than the other methods and is more applicable in situations where missing tests or irregular test intervals are frequently encountered in milk recording system.

Dry period length and performance of cows in the subsequent production cycle

Abstract. The effect of dry period length on performance in the next production cycle was investigated in the active population of cows from the Pomerania and Kuyavia regions of Poland. Dry length period of the cows was calculated and classified (0, 1–20, 21–40, 41–60, 61–80, 81–100, &gt;100 days). The GLM, FREQ and CORR PEARSON procedures of the SAS package 9.1 were used in the statistical calculations. The problem of dry period length was found to be debatable. A dry period of 40–60 days would be the most favourable in terms of milk, fat and protein yield in the next lactation, the course of parturition and the proportion of calves born alive, and a dry period of 21–60 days would be the most beneficial in terms of the proportion of cows surviving the next production cycle. Extending or shortening the standard dry period of 40–60 days by 20 days causes a slight decrease in performance determined by the above parameters, whereas extending and especially shortening the dry period by another 20 days, or the absence of a dry period, have a severely negative effect. Compared to cows that had been dry for 40–60 days, the cows whose calving was not preceded by a dry period had lower lactation yield (by 25 % for milk, by 24 % for fat and by 20 % for protein), lower daily milk yield (by 22 %), were significantly more prone to miscarriage, and more frequently gave birth to dead calves, calves with physical defects or grossly malformed calves. Too long a dry period (beyond 100 days) may carry a risk of higher culling levels in the herd, shorter lactations, health abnormalities, and poorer reproductive performance.

Synthesis and characterization of a novel poly(ester-urethane) containing short lactate sequences and PEG moieties

A novel poly(ester-urethane) with tailor-made structure was prepared by using lactic acid (LA) as starting material through a combination of two facile common reactions. First, a diol was prepared via the esterification between LA and poly(ethylene glycol) (PEG) with low molecular weight. Subsequently, the poly(ester-urethane) was synthesized through the addition polymerization of the LA-based diol and toluene 2,4-diisocyanate with 1,4-butanediol as chain extender. The structure, morphology, and properties of intermediate and the poly(ester-urethane) were analyzed with Fourier transform infrared spectroscopy, proton nuclear magnetic resonance, gel permeation chromatography (GPC), X-ray diffraction, differential scanning calorimetry, polarizing optical microscopy, and thermogravimetric analysis. The results indicated that the intermediate was a diol of conjugating quite short lactate sequences with PEG oligomer, and the structure of the poly(ester-urethane) was as expected. The thermal transition, thermal decomposition temperature, and crystallinity of the polymer samples depended on the molecular size of PEG. In vitro degradation property of the poly(ester-urethane) also relied on the molecular weight of PEG. The weight loss percentages varied from 11 to 36% after 12-days immersing in phosphate-buffer saline at 37°C. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013

LACTATION CURVE AND PHYSIOLOGICAL REACTION FOR EGYPTIAN BUFFALOES UNDER DIFFERENT ENVIRONMENTAL CONDITIONS

The data used in this study were collected from two milking buffalo's farms .These farms are located at different geographical regions, one in the old land (village) and the other in reclaimed land (new land) in Alkobabat village, Atfeh city, Giza governorate. 50 dairy buffalo cows (3th and 4th parity), 25 animals in each, the first (farm 1) in the village and the second (farm 2) in the reclaimed land called Abou-Sroor land. The objective of the present investigation was to describing the lactation curve, calculate the persistency of lactation, total milk yield, daily milk yield and lactation period, and also to study physiological response for buffaloes under environmental conditions in the old land (village) and the reclaimed land. The results, found that the total milk yield and daily milk were higher in farm 1 than in farm 2. The daily milk yield (kg/day) was higher nearly 1 kg. Farm 2, have salinity in drinking water. The persistency value was higher in farm 2, although short lactation period were observed. Accordingly, buffalo breeding in the reclaimed land give good milk production traits.

Patterns of reproduction in Malayan silvered leaf monkeys at the Bronx Zoo

Within phylogenetic limits reproductive characteristics of a given species may vary between populations in response to ecological and social factors. For instance, in environments where high quality nutrition is readily available, the onset and speed of reproduction are often accelerated. Other influencing factors might be maternal experience or the sex of the infant. Here we present data on reproductive characteristics for the silvered leaf monkey (Trachypithecus cristatus), a medium-sized Asian colobine housed at the Wildlife Conservation Society's Bronx Zoo as a one-male group. To place the species into an appropriate phylogenetic context, we limited our comparison to other colobine species. Demographic data span 21.4 years (October 1985 to March 2007) and derive from 30 adult females (128.0 female years). Detailed behavioral data stem from a 2.2 years study (November 2002 to January 2005; 734 days, 4,225 hr). As in other Asian colobines, receptive periods were short (mean=4.3 days, n=68). This is expected for one-male groups where receptivity likely indicates, rather than conceals, ovulation. Gestation length was estimated based on a change in the pattern of sexual behavior (mean=194.6 days, n=7). It fell within the range reported for the taxon. Births occurred year round, at an early age (mean=2.9 years, n=8), at short intervals (mean=14.9 months, n=59) in combination with a short lactation (mean 12.1 months, n=9) likely due to the nearly unlimited availability of nutrition in this zoo setting. Primiparous females tended to have a longer first interbirth interval but infant survival rates were similar to multipara possibly due to the absence of predators. Maternal investment was independent of the infant's sex and birth sex ratio was even. Our results emphasize that when interpreted with caution, zoo populations yield realistic reproductive characteristics that can help fill the gap in our knowledge about colobine life history.

Factors associated with return to estrus in first service swine females

Reproductive failure is a major factor contributing to the culling rate of swine females. As return to estrus is the most frequent reproductive failure, the study of factors associated with its occurrence can help to identify females with a predisposition to this failure. This study was run in a farm with a housing capacity of 1500 Agroceres PIC ® females in southern Brazil. Logistic regression models were run to determine the relative contribution of some factors to the probability of a sow returning to estrus. Return to estrus occurred in 27.8% (10/36) and 10.7% (50/469) of females remated after a previous reproductive failure and first service females, respectively. Females with a previous reproductive failure had 3.2-times higher odds ( P = 0.003) of returning to estrus than first service females. In first service females ( n = 469), higher odds ( P < 0.05) of returning to estrus were observed in parity order (PO) 0 (14.3%; 3.1-times), PO1 (20.6%; 4.9-times) and PO2 (12.7%; 2.7-times) compared to PO>2 (5.0%; reference class) females. Weaned females with ovarian cysts, detected during estrus, had 7.6-times higher (37.5%; 3/8) odds ( P = 0.012) of returning to estrus than females without cysts (8.3%; 28/338). In the model run with 330 weaned sows, the return to estrus rate was not affected ( P > 0.05) by the number of weaned piglets (7–9; 10; 11 and 12 piglets) but sows with a lactation length (LL) of 15–19 days had 3.5-times higher odds ( P < 0.05) of a return to estrus than sows with LL of 20–21 days. Return to estrus in weaned sows was also affected by the interaction between PO and body condition score (BCS) loss during lactation. Loss of more than 0.5 point in BCS resulted in higher odds ( P < 0.05) of returning to estrus in PO1 and PO2 but not in PO>2 sows. Accurate detection of estrus in gilts and adequate feed intake during lactation of first and second parity sows are suggested to reduce return to estrus rate in younger females. To avoid the detrimental effect of short lactations on reproductive performance options such as increasing the lactation length, split-weaning or skip-mating may be considered.

Influence of fermentable carbohydrates on the intestinal bacteria and enteropathogens in broilers

The gastrointestinal tract is a complex milieu as a result of interaction between dietary ingredients and the intestinal bacteria. Following the European ban on the use of in-feed antibiotics, research has focused mainly on the potentially beneficial activities of the intestinal microbiota. Fermentable carbohydrates, or ‘prebiotics’, such as non-digestible oligosaccharides, are considered to have beneficial effects on the composition and activity of the indigenous microbiota, which can enhance the resistance of the host against colonisation of pathogenic bacteria in the GIT. Only a limited number of prebiotics has been tested in broilers that include fructo-oligosaccharides, inulin, mannan-oligosaccharides, alpha gluco-oligosaccharides, isomalto-oligosaccharides, different kestoses and lactose along with its derivatives. This review provides an overview pertaining to the potential impact of prebiotics on the intestinal bacterial population in broilers and summarizes the data regarding the role of prebiotics in preventing the colonisation of enteropathogens especially Salmonella spp., Campylobacter spp. and Clostridium spp. Moreover, the influence of prebiotics on the intestinal bacterial fermentation profile, particularly short chain fatty acids, ammonia and lactate, is also discussed. Prebiotics have been found to affect the intestinal bacterial population particularly elevating the caecal count of Lactobacillus spp. and Bifidobacterium spp. The effect of prebiotics on the intestinal bacteria is also evident in terms of change in the total concentration or relative proportion of short chain fatty acids. The ability of prebiotics in controlling the colonisation of different enterpathogens especially Salmonella spp., Clostridium perfringens or Campylobacter spp. showed inconsistent results depending upon the available literature.

Relationship of vaginal impedance with speed of return to oestrus after weaning, oestrous behaviour, parity and lactation length in cyclic sows

The effect of weaning to oestrus interval, oestrus duration, parity, lactation length, breed and their interactions on changes of vaginal impedance in sows after weaning and during oestrus was examined. The impedance measurements were carried out by a four-electrode method. The interval from weaning to oestrus was significantly longer in sows with the length of lactation 21–25 days than 26–30 days and 31–36 days and in primiparous than multiparous sows. The interval from weaning to oestrus was negatively correlated with the length of lactation ( r = −0.21; P < 0.05), parity ( r = −0.36; P < 0.01) and oestrus duration ( r = −0.26; P < 0.01). The weaning to oestrus interval, oestrus duration, parity and lactation length had a significant effect and the breed of sows had no influence on the vaginal impedance in peri-oestrus. The decrease of vaginal impedance after weaning was delayed in sows with a longer weaning to oestrus interval and in primiparous than multiparous sows. The decline of vaginal impedance during peri-oestrus was more gradual in sows with a longer interval from weaning to oestrus, shorter lactation, primiparous sows and sows with the length of oestrus 36 h and 72 h and more. The nadir of vaginal impedance occurred earlier before oestrus in sows with a shorter oestrus. The interaction of weaning to oestrus interval with parity and oestrus duration and the interaction of oestrus duration with parity significantly affected the vaginal impedance in weaned sows. In conclusion, the weaning to oestrus interval, oestrus duration, parity and lactation length considerably influence the vaginal impedance in sows during peri-oestrus. The findings indicate that the impedance technique may be a useful method for a study of factors and processes that accelerate or slow down the return to oestrus after weaning and affect oestrus duration in sows.

Data transformation for rank reduction in multi-trait MACE model for international bull comparison

Since many countries use multiple lactation random regression test day models in national evaluations for milk production traits, a random regression multiple across-country evaluation (MACE) model permitting a variable number of correlated traits per country should be used in international dairy evaluations. In order to reduce the number of within country traits for international comparison, three different MACE models were implemented based on German daughter yield deviation data and compared to the random regression MACE. The multiple lactation MACE model analysed daughter yield deviations on a lactation basis reducing the rank from nine random regression coefficients to three lactations. The lactation breeding values were very accurate for old bulls, but not for the youngest bulls with daughters with short lactations. The other two models applied principal component analysis as the dimension reduction technique: one based on eigenvalues of a genetic correlation matrix and the other on eigenvalues of a combined lactation matrix. The first one showed that German data can be transformed from nine traits to five eigenfunctions without losing much accuracy in any of the estimated random regression coefficients. The second one allowed performing rank reductions to three eigenfunctions without having the problem of young bulls with daughters with short lactations.

Economic opportunity survey of small scale dairy farms of the north west province of Cameroon

An Economic Opportunity Survey was conducted on dairy farms in the North West Province of Cameroon. Results showed that median (range) number of cows in milk per farm was zero point six (0-4) and six (3-12) in the zero grazing and transhumance systems, respectively. Medians (range) of three (0-24) and four (3-10) litres of milk were sold per farm per day, corresponding to 30% and 60% of milk produced. 24% and 13% of total cattle per herd were milking cows in the zero grazing and transhumance systems respectively. Median milk production per cow on one day was two (0-25) and two (1-3) litres. Median calf production interval was 14.5 (12-25) and. 21.5 (14-29) months. More milk produced per day represented the best economic opportunity in both systems while reduced age at first calving and longer lactation length were the next in both. Wastage of milk through spoilage from poor hygiene and lack of cooling was a major problem. Holstein cows, which were in the zero grazing system, had unexpectedly short lactations. Constraints identified led to the setting up of interventions of training and advice for farmers and of better nutrition.

Influence of Breastfeeding in the Accumulation of Polybromodiphenyl Ethers during the First Years of Child Growth

The concentrations of polybromodiphenyl ethers (PBDEs) in children at birth (cord blood sera, n = 92) and at the age of 4 years (sera, n = 244) from a cohort established in Menorca Island (Balearic Island, Spain) were studied. This cohort is representative of a general European population that is fed a typical Mediterranean diet. Among the 13 congeners analyzed, BDE #47 was the most abundant in both types of samples, with mean values of 2.8 ng/g of lipid weight in cord blood sera and 2.9 ng/g of lipid weight in sera. The observed distributions of PBDEs paralleled the composition of the commercially available mixtures of pentabromodiphenyl ethers. The concentrations of most congeners were higher in females than in males, but the differences were not significant. PBDE in the sera of 4 year old children was higher among those having been fed with maternal milk than formula. The differences were statistically significant for the congeners found in higher concentrations (e.g., BDE #47 and BDE #99). This difference was consistentwith previous reports on polychlorobiphenyls or 4,4'-DDE, indicating that despite the short lactation period (about 4.5 months as an average in this cohort), breastfeeding was the determining factor for the body burden of these compounds at 4 years of age. The observed increases of average body burden of total PBDEs between birth and the first 4 years of growth were 65 and 10 ng for breastfed and formula fed children, respectively.

Lactation and mother–pup behaviour in the Mediterranean monk seal Monachus monachus: an unusual pattern for a phocid

This paper presents baseline information on maternal behaviour and lactation in the Mediterranean monk seal, with particular focus on the age at which pups are weaned. The study was conducted in the western Saharan population, the only surviving colony of the species. The first moult finished at a mean pup age of 72.3±17 d (N=17) and, in contrast to other taxonomically-related phocids, this process was not associated with weaning. Lactation lasted a mean of 119.4 d (N=9; range: 103–149 d) in the pups that could be monitored until full weaning had taken place. This period almost doubles the maximum lactation length reported in other phocid species. During the first week after birth the mother–pup bond was well developed and mothers always remained with their pups. The time invested in nursing (17%, SD: ±36) and in mother–pup interactions (14%, SD: ±32) was higher during this period than afterwards (8%, SD: ±23 and 4%, SD: ±19, respectively). After the first week, nursing continued but mothers started to leave their pups in order to feed at sea. Weaning occurred gradually. Already since birth, pups were active and mobile, and swam frequently before moulting or weaning occurred. Fostering and milk stealing were common patterns of behaviour for both lactating females and pups. In 26.6% of the suckling episodes observed in mother–pup pairs of known identity, pups suckled from females other than their mothers. Some females nursed more than one pup, at least occasionally, and in some cases a pup was fostered long-term by an alien female. The Mediterranean monk seal exhibits maternal-care characteristics that are more like otarids than phocids. This observation contradicts previous proposals that a short lactation period is a phylogenetic characteristic of phocids. Several of the unusual maternal traits observed may be favoured by year-round access to abundant food supply, availability of breeding sites, and mild climatic conditions. This information should be taken into account when designing conservation strategies for the species and, very particularly, in the implementation of pup rehabilitation programmes.

Longevity of buffalo cows and reasons for their culling

Subject of investigation were 565 buffalo cows from the Bulgarian Murrah breed, raised at the Agricultural Institute – Shumen for the period 1989-2003. The reasons for culling included: sclerosis of ovary, nymphomania, tumors of uterus, occlusion of cervix, concrescence of uterus, endometrites, low productivity (below 200 kg for 120 lactation days), gastrointestinal disorders, old age (over 12 years), short lactation period (below 120 days), respiratory diseases, prolepses and upset metabolism. It was established that the average longevity of buffaloes was 2636 days. The part of buffalo cows culled for gynecological reasons was the biggest -41 %, followed by low productivity -19 %, prolapses -11 %, short lactations -7 % and old age -9%. The most animals were culled at first lactation -25.9 %.