Short Lactation Research Articles

Effects of cold storage and freezing on sheep’s milk

Sheep’s milk production in Brazil is focused on the industrialization of high added value derivatives. Some factors, such as seasonal production, short lactation period, and microbiological contamination, cause a shortage of this raw material throughout the year. It is well known that low temperatures are used in the conservation of dairy products and the objective of this study was to verify the microbiological and physical-chemical quality in refrigerated and frozen raw sheep’s milk. Standard plate counts, psychrotrophics, Staphylococcus aureus, total coliforms, and fecal coliforms, as well as titratable acidity, pH, and water activity were analyzed in samples 1 day after refrigeration and 8 and 15 days after freezing temperatures. Overall, the results of refrigerated milk were based on the legislation, but frozen milk showed high values of aerobic plate, S. aureus, and acidity, especially after 15 days of storage. Psychrotrophics and coliform counts were also high, indicating a risk for the quality of the raw milk and derivatives, which emphasizes the importance of handler training for good practices in the farm, as well as in the dairy industry. Freezing may be a viable strategy; however, additional studies testing lower temperatures and previous milk pasteurization are necessary to guarantee milk quality and consumer safety.

Breeding pure and crossbreeds of European cattle breeds for milk production improvement under tropical climate conditions-a review.

The aim of this review was to present the breeding status of pure or crossbreeds of European cattle with African indigenous cattle in order to improve milk yield in African tropical conditions. As the African indigenous breeds are characterized by small size, low body weight (300-450 kg) and low production performances (less than 1000 kg per lactation), short lactation length (205-240 days), etc., the crossbreeding with pure European cattle was done in order to ameliorate production performances especially milk and beef production. As results, it was seen that F1 offspring improved output productions than their parents of tropical origin. Also, it was seen that F1 offspring showed disease and heat resistance than their parents of temperate climate origin. However, at different degrees of crossbreeding, it was seen that the offspring can demonstrate bad production performances than their parents and therefore, the crossbreeding has to respect a certain degree. Other consequences are that the crossbreeding of local and pure European cattle breeds has resulted in calving complications in African local cattle. In African indigenous cattle, the selection as an improvement tool was given less emphasis as a solution to improve output production. That is why, the implementation of a well-prepared selection programs could be practiced in African indigenous cattle in order to preserve African cattle genotypes, as they are endangered of extinction due to various crossbreeding with exotic cattle breeds.

Effect of Restricted Suckling on Shortened Lactation Length and Performance of Sahiwal Cattle

Background: Sahiwal cattle write is more prone to lactation failure and short lactation. The present study was conducted to study effects of restricted suckling on productive (with special reference to lactation length) and reproductive performance of Sahiwal cows, who had short lactation length. Methods: A total of 24 multiparous Sahiwal cows of 2nd-4th parity were selected based on their previous history of short lactation length (70-190 days). Cows were randomly divided into 3 weaning groups i.e. zero day weaning group (G1, n=8), restricted suckling up to 90 days (G2, n=6) and restricted suckling up to 150 days (G3, n=6). Recording of peak yield (PY), lactation milk yield (LMY) and lactation length (LL), udder morphometry, somatic cell count (SCC), milking behaviour and reproduction parameters was done. Blood plasma levels of prolactin (ng/ml), growth hormone (mg/ml) and cortisol (ng/ml), were also studied. Result: Lactation MY (kg) was found highest in G2 followed by G3 and G1. Lactation length was found significantly (p≤0.05) longer in group-3. Temperament scoring, days to first heat and service period of cows found significantly higher in RS groups. Overall improvement in lactation length was 38.27% in G2 and 37.28% in G3 as compared to their previous LL. So, the study indicated that the restricted suckling method seems to be more efficient compared to an immediate calf separation since this avoided the cow becoming dry prematurely, improved milk yield, lactation length and growth rate of calves.

N-glycan profiles as a tool in qualitative and quantitative analysis of goat milk adulteration

Goat milk is closer to human milk in some respects than cow milk, and therefore preferred by many consumers. Because of the short lactation period and consequently less milk production of goats, the price of goat milk is often higher than that of cow milk, so that adulteration of goat milk is common. N-glycans have stability and thus have a good potential for acting as a new biomarker for identifying dairy adulteration. In this study, the N-glycan structures of goat milk and cow milk were analyzed by Ultra-high performance liquid chromatography (UPLC) and MALDI-TOF-MS. Based on the high species specificity of N-glycans, a method for identifying goat milk mixed with cow milk was established. The adulteration content of 5% cow milk in goat milk could be qualitatively and quantitatively detected. A prediction model of adulteration in goat milk was established by using partial least squares (PLS).

Embryonic-placental relationship in Lagostomus maximus as compared to other hystricognath rodents and eutherian mammals

Reproductive specializations in caviomorphs (infraorder Hystricognathi), are very peculiar within the Order Rodentia. These include long gestations, the birth of offspring with an extreme degree of precociality, and short lactation periods. This study describes the embryo-placental relationship of viable implantation sites (IS) of the plains viscacha, Lagostomus maximus, after 46 post-coital days. The observations recorded in this study are comparatively discussed with those of other hystricognaths and eutherians. At this stage, the embryo resembles that of other eutherians. At this time of embryo development, the placenta exhibits a size, shape, and organization similar to that it will have in its mature state. Besides, the subplacenta is already highly folded. These characteristics are adequate to sustain the development of future precocial offspring. The mesoplacenta, a structure present in other hystricognaths and related to uterine regeneration is described for the first time in this species. This detailed description of the placental and embryonic structure contributes to the knowledge of the reproductive and developmental biology of the viscacha, as well as that of hystricognaths. These characteristics will allow testing other hypotheses related to the morphology and physiology of the placenta and subplacenta, and their relationship with the growth and development of precocial offspring in Hystricognathi.

Prevalence and Associated Risk Factors of Postpartum Anestrus in Dairy Cows of Sylhet District, Bangladesh

The objectives of current study were to assess the prevalence and risk factors associated with postpartum anestrus in lactating dairy cows in Sylhet region, Bangladesh. A total of 420 postpartum cows of different breed and age were selected randomly from different dairy farms in studied area. Structured questionnaire was used to collect data from farm owner on prevalence and risk factors for postpartum anestrus. Observed heat within 60 days after parturition was considered as normal cyclic cows and others were considered as postpartum anestrus. The prevalence of postpartum anestrus was 36.20%. The study shows that older cows take relatively more time for ovarian resumption. Cow’s having first parity shows cyclicity within 60 days of parturition, and postpartum anestrus increases significantly with the advancement of parity. Postpartum anestrus was significantly higher (P< 0.001) in cows with poor (≤1.0) and excessive (>3) body condition scores (BCS), respectively, compared to those with moderate/optimal BCS (2–3). The postpartum cyclicity in cows within 60 days with a history of normal placental expulsion was significantly higher than in the cows with RFM. Ovarian cyclicity was highest (75.92%) among the cows that were maintained in adequate hygienic conditions and lowest (43.51%) in a poor environment. The highest percentage (88.10%) of cows showed postpartum cyclicity with a history of short lactation length (0-150 days) and resumption of postpartum estrous cycle increases significantly with lactation length. Resumption of postpartum estrus cycles in cows takes more time with a history of minimal (<15 liters) daily milk production than the cow with medium (>15-25 liters) daily milk production. Cows get an adequate feed supply (both concentrate and green grass), which shows a positive effect on postpartum cyclicity. Pre and postpartum complications have a significant (p<0.001) effect on the postpartum cyclicity of cows. Endometritis (81.25%) followed by pyometra (75.76%) were recorded as major reproductive obstacles in ovarian resumption, whereas uterine prolapse (70.59%) followed by abortion (61.54%), milk fever (58.33%), stillbirth (58.33%) and dystocia (57.63%) were the major recorded complications in post-partum phase. The study also revealed that the non-restricted suckling period has a significant (p<0.001) negative effect on ovarian resumption. The risk factors including parity, BCS, placental expulsion, hygienic condition, lactation length, daily milk production and management system were significantly (P<0.01) influenced the postpartum cyclicity. Maintaining optimal BCS of cows, proper hygienic and good management practice, and farmer's training on management of cattle reproduction would improve the number of cows for breeding by 60 days postpartum.

Age as a primary driver of the gut microbial composition and function in wild harbor seals

Dietary changes are the major variation cause in the composition of the gut microbiota. The short lactation phase in phocids provides an exceptional opportunity to explore the microbiota's response to a quick transition from a milk-based to a solid diet. We investigated the effects of age and sex on the gut microbiota of harbor seals in Mexico using rectal and fecal samples from pups and adults. 16S gene sequencing revealed age explains most of the observed variations in microbial composition. Individuals with frequent contact (pups—female adults) have major microbial similarities than those with little or no contact (pups—male adults). Overall, adults and females (regardless of sex and age, respectively) have a greater microbial richness; as seals grow, the core microbiome shrinks, and microbial diversity increases. We found pathways related to milk and chitin digestion in pups' microbiomes, indicating pups were transitioning to a solid diet. An enrichment of routes related to dramatic weight loss and body mass indicated higher metabolic stress in pups in late breeding season, when they are weaned and start intermittent fasting. Our findings highlight the host-microbiome interaction in harbor seals during late breeding season in response to food shifts and metabolic stress.

Comparative Characteristics of the Amino Acids Composition of Sheep Milk from Breeds of Northern Kazakhstan

Kazakhstan is characterized by a wide variety of natural, climatic, economic, and ethnic factors that have a specific impact on the development of sheep farming. The production of dairy products from sheep is limited due to the low productivity of animals and the seasonality of milk production throughout the year, as well as the short lactation period. Also, one of the problems is manual milking of sheep, which does not allow obtaining sheep milk on an industrial scale. The market of dairy products, currently in the Republic of Kazakhstan is represented only by-products made from cow's milk, and at the same time, most of them are products made from cow's milk powder, so the development of products made from sheep's milk is an urgent task. In addition, sheep's milk is a national product, and one of the tasks is to revive the traditional products of the Kazakh people. The analysis of literature studies shows that in-depth studies of the chemical composition of sheep's milk have not been conducted in Kazakhstan. The chemical composition data obtained during the Soviet period only give an idea of the primary chemical parameters obtained by generally accepted basic methods and do not provide reliable information about the deep chemical composition of the milk of local ewes. According to the results of studies, the content of the essential amino acid valine in cow's milk (0.21 g/100g) is also lower than in sheep's milk (9.69-3.79 g/100g). Sheep's milk protein is digested in the human body by 99.1%, and cow's milk protein by 91.9%. According to world experts, one of the advantages of Kazakhstan's domestic milk products is its naturalness, a low share of the use of genetically modified organisms, and environmentally friendly pastures, due to which they receive high-quality and safe products. Therefore, the designated research topic and its analysis are appropriate and relevant.

The influence of lactation and its duration on bone mineral density in pregnancy and postpartum: A systematic review with meta-analysis.

There is a plethora of research on the association of parity and duration of lactation with bone mineral density (BMD) during and after pregnancy. However, there are no consensus conclusions on the impact of the duration of lactation on BMD. The aim of this study was to examine the effect of pregnancy, and the duration of lactation on BMD during pregnancy, postpartum phase and 12 months post-delivery. The search terms 'parity' 'lactation' 'BMD' were searched for using PubMed, CINAHL, SCOPUS and EMBASE databases in English language. Two independent reviewers assessed the quality of the included studies using Critical Appraisal Skills Program (CASP) appraisal tool and extracted data on BMD (g/cm2) in Excel. A meta-analysis was conducted with a random effect model using Cochrane Review Manager (Rev 5.4) to analyse the outcome. Heterogeneity was assessed with Chi Squared and I2 test. The duration of lactation was grouped into short lactation duration (SLD), ≤4 months and longer lactation duration (LLD)>6 months. Twenty-one studies were included in this review with four studies included in the meta-analysis. BMD reduced during pregnancy and lactation. Recovery and net gains in BMD followed weaning. However, at 12 months postpartum, women in the LLD group had significant losses at the lumbar spine while those in the SLD recovered BMD. Between the SLD and LLD groups, the change in BMD was not significant 0.48g/cm2 (95% CI -0.14, 1.10, p=0.13). BMD losses were greater in primiparous women than multiparous women. Women who breastfed for >6 months had significantly reduced BMD. However, compared to women that breastfed for a ≤4 months there was no significant change in BMD. Further investigation is needed to clarify the association between lactation and BMD in a postpartum population in those women extending breastfeeding beyond one year.

Tracking wildlife energy dynamics with unoccupied aircraft systems and three‐dimensional photogrammetry

Abstract We present a novel application using unoccupied aircraft systems (UAS; drones) for structure‐from‐motion three‐dimensional (3‐D) photogrammetry of multiple, free‐living animals simultaneously. Pinnipeds reliably haul out on shore for pupping and breeding each year, accompanied by dramatic female‐to‐pup mass transfer over a short lactation period and males lose mass while defending mating territories. This provides a tractable study system for validating the use of UAS as a non‐invasive tool for tracking energy dynamics in wild populations. UAS imagery of grey seals Halichoerus grypus was collected at Saddle Island, Nova Scotia. A multirotor UAS was piloted in 360‐degree orbits around relatively dense animal aggregations and georeferenced images were used for construction of a 3‐D point cloud, orthomosaic and Digital Surface Model for animal volumetric measurements. Directly following UAS survey, a subset of adult females were hand‐measured (morphometrics, blubber depth, n = 21 handlings [15 were unique animals]) and female–pup pairs were weighed (adult females: n = 32 [24]; pups: n = 33 [23]) to validate that UAS 3‐D photogrammetric models provided accurate animal volume and mass estimates. UAS two‐dimensional body length measurements were sensitive to animal recumbency and posture. The new UAS 3‐D photogrammetric method overcame these constraints, and aerial‐derived body volume measurements were equivalent to those collected from the ground. UAS body volume measurements precisely predicted ‘true’ body mass (mean absolute error, adult female: 3.8 kg, 2.1% body mass; pup: 4.1 kg, 9.8%), and exhibited a stronger relationship with total body mass than with blubber volume. The method was applied to 673 free‐living animals to characterize volume and mass dynamics across lactation and breeding for a much larger sample size than would be possible using traditional ground methods. Indeed, 1–46 animals (M ± SE: 9.2 ± 1.2) were modelled concurrently within the focal area of a UAS flight. Application of the method also captured significant inter‐annual variation in body volume/mass dynamics, and female‐to‐pup energy transfer efficiencies were lower when there was low sea ice extent. The UAS 3‐D photogrammetric method presented in this study is likely to be broadly applicable to other species, and the ability to measure whole groups of free‐living animals at once makes strides towards ‘weighing populations’.

Incidence of unintended pregnancy within 2 years after delivery and its influencing factors in China

Objective: To investigate the present situation of unintended pregnancy within two years postpartum and its influencing factors in China. Methods: Participants who delivered a live birth at 60 hospitals in 15 provinces in the eastern, central and western regions of China during July 2015 to June 2016 were interviewed by using structured questionnaire. Information on occurrence of unintended pregnancy within 2 years after delivery, postpartum contraceptive use, sexual resumption, breastfeeding, and women's socio-demographic characteristics, and so on, were collected. Life-table analysis, cluster log-rank tests and a 2-level Cox regression model were used for data analysis. Results: A total of 18 045 postpartum women were investigated. The cumulative 1- and 2-year unintended pregnancy rates after delivery were 5.3% (95%CI: 4.5%－6.1%) and 13.1% (95%CI: 11.3%－14.8%), respectively. Cox regression model analysis showed that the risk of unintended pregnancy within 2 years postpartum were increased in younger women, ethnic minorities, women with abortion history, and those who had a vaginal delivery with short lactation time and late postpartum contraceptive initiation (all P<0.01). The risk of postpartum unintended pregnancy was not associated with geographic regions and hospitals where women gave a birth (all P>0.05). Conclusions: In China, the risk of unintended pregnancy within 2 years after delivery is relatively high. Service institutions and service providers should improve the quality of postpartum family planning services, promote the use of high effect contraceptive methods, and educate women to use a method at the time of their sexual resumption or even before.

Performance Evaluation of Arsi, Kereyu and Their Crossbred Cattle Under Current Climate Change in Mid Rift Valley of Oromia, Ethiopia

The study was conducted in Fentale and Boset districts, East Shoa Zone, Oromia Region, Ethiopia. The objective of this study was to identify morph metric variation between cattle breeds of Arsi, Kereyu and their crossbred, and to evaluate adaptive, productive (milk yield) and reproductive performance of these cattle breeds, and their crossbred in the mid rift valley of Oromia Region. Three PA’s from each district, a total of Six PA (Huluka, Kawa, Barchota, Benti, Kobo and Dakaedu) were selected purposively. Respondents’ were identified using purposive sampling technique. Kereyu, Arsi and crossbred cattle of the two were reared for, milk production, risk aversion and source of income. The major production constraints identified were feed shortage, water scarcity, disease and coverage of grazing land by invasive plants. Arsi cattle’s have long age at first mating (3.87±.17), age at first calving (4.66±0.2) and calving interval (1.50±0.125) than Kereyu (3.78±0.23, 4.52±0.25, 1.39±0.19) and crossbred (3.86±0.11, 4.64±0.12, 1.49±0.14) in both study location while the crossbred cattle have medium Values respectively. Arsi cattle have short Lactation length than kereyu and Crossbred (6.36, 7.51, 7.11months for Arsi, kereyu and crossbred respectively also similar for daily milk yield (1.26, 1.71 and 1.43). The farmers in the two district prefer Kereyu breed due to their ability to tolerate drought, disease and highly adaptable to the area where as Arsi breed of cattle was susceptible to feed shortage, water scarcity and disease than other breed in the area. This study revealed that the Arsi community in the study area prefers to mate breeding female of Arsi with bull of Kereyu breed.

Identification of maximal lactate steady state by a short lactate minimum test in walking

The purpose of this study was to analyze the validity of a short Lactate Minimum test (LM) to assess the maximum lactate steady state (MLSS) during walking tests. Twelve healthy young participants performed LM on a treadmill at 5.5 km·h −1 , with the intensity being incremented by inclination (%). Participants first performed a walking trial at 5.5 km·h −1 with 20% or 22% inclination until voluntary exhaustion. After 7 min of recovery an incremental test was initiated by using only 3 incremental stages that were selected based on the rate of perceived exertion (RPE). The LM intensity was identified as the lowest [bLac] during the incremental test, by using a visual inspection (LM3v) and applying a polynomial function of second order (LM3p). The MLSS intensity was also measured. ANOVA showed no difference between the intensities (i.e., treadmill inclination) of MLSS (13.3 ± 2.2%), LM3 v (12.6 ± 1.6%), and LM3p (13.4 ± 1.3%). It was possible to identify the LM during walking by using 3 stages in most of the participants expressing the MLSS intensity with good agreement and correlation between them. Le but de cette étude était d’analyser la validité d’un test lactate Minimum (LM) pour évaluer l’état stable de lactate (MLSS) pendant les tests de marche. Douze jeunes participants en santé ont effectué LM sur un tapis roulant à 5,5 km0h-1, l’intensité étant augmentée par l’inclinaison (%). Les participants ont d’abord effectué un essai ambulant à 5,5 km0h-1 avec une inclinaison de 20 % ou 22 % jusqu’à l’épuisement volontaire. Après 7 min de récupération, un test incrémental a été initié en utilisant seulement 3 étapes incrémentales sélectionnées en fonction du taux d’effort perçu (RPE). L’intensité LM a été identifiée comme la plus faible [bLac] pendant le test incrémental, en utilisant une inspection visuelle (LM3v) et en appliquant une fonction polynomiale de second ordre (LM3p). L’intensité MLSS a également été mesurée. L’Anova n’a montré aucune différence entre les intensités (c’est-à-dire l’inclinaison du tapis roulant) de MLSS (13,3 ± 2,2 %), LM3 v (12,6 ± 1,6 %) et LM3p (13,4 ± 1,3 %). Il a été possible d’identifier le LM pendant la marche en utilisant 3 étapes dans la plupart des participants exprimant l’intensité MLSS avec un bon accord et une corrélation entre eux.

Sow-related factors affecting the postweaning feed intake in Landrace × Large White females.

During the weaning-to-estrus interval (WEI), a high feeding level is usually offered to recover losses due to lactational catabolism. However, several factors can affect the appetite, possibly impairing the efficacy of this strategy. This study aimed to investigate the effect of sow-related factors on average daily feed intake (ADFI) during WEI in 142 primiparous and 458 multiparous sows. After weaning, the sows received 4.3 kg/day of feed and the wastage was recorded. The ADFI after weaning was lower in primiparous than multiparous sows, and on estrous day than in 2 and 3 days preceding estrus (P ≤ 0.05). In primiparous sows, lower ADFI was observed if they had higher backfat thickness at 112 days of gestation (BFT ≥ 11.5 mm) or higher reserves at weaning (BFT ≥ 10.5 mm, caliper units ≥ 12 or ≥ 157 kg; P ≤ 0.05). Higher body reserves at the end of gestation (caliper units ≥ 12, BFT ≥ 11.0 mm, or BCS ≥ 3.0) or weaning (caliper units ≥ 13, BFT ≥ 12.5 mm) negatively affected the ADFI in multiparous sows (P < 0.04). Weaned litter size ≤ 11 piglets (P = 0.06) and shorter lactation length (P< 0.01) decreased the ADFI in primiparous sows. Greater loss in caliper units during lactation tended to reduce ADFI in primiparous and multiparous sows (P ≤ 0.07). Multiparous sows with greater losses in BFT and BCS had lower ADFI (P ≤ 0.03). The ADFI during WEI is reduced when sows are in estrus or if they have greater body reserves.

Screening of frozen-thawed conditions for keeping nutritive compositions and physicochemical characteristics of goat milk

Frozen milk can help producers overcome the seasonality of goat milk production, low goat production and short lactation periods, and avoid discarding milk during some special periods. We investigated effects of combination between freezing (cryogenic refrigerator of -16 to -20°C or ultra-cryogenic refrigerator of -76 to -80°C) and thawing (homeothermy of 20 to 25°C or refrigeration of 2 to 4°C) on nutritive compositions and physicochemical characteristics of raw goat milk during storage period (80 d). Compared with fresh goat milk, the frozen-thawed milk decreased contents of fat, protein, and lactose, as well as surface tension and stability coefficient, whereas increased effective diameter and polydispersity index. The average values of color values (L*, a*, and b*) in 4 group samples changed from 83.01 to 82.25, -1.40 to -1.54, 3.51 to 3.81, respectively, and the ΔE of most samples did not exceed 2. In contrast to the other 3 frozen-thawed treatments, goat milk treated with ultra-cryogenic freezing-homeothermic thawing (UFHT) possessed higher fat (5.20 g/100 g), smaller effective particle diameter (0.32 µm), and the lowest polydispersity index value (0.26). The color and confocal laser scanning microscopy images of UFHT were similar to those of fresh goat milk, illustrating UFHT was the optimal approach to maintain the natural quality of goat milk. Our finding provides a theoretical basis for producers to freeze surplus milk.

Abnormal Lactation Lengths and its Consequences on Performance of Crossbred Cattle

Background: The study was conducted to unravel the consequences of abnormal lactation lengths (Extremely short, short, prolong and extremely prolong lactation length) on production and reproduction traits of crossbred cattle (Red Dane x Sahiwal x Holstein Friesian), which otherwise remains unutilized in routine breeding data analysis owing to normalization and standardization of lactation lengths. Methods: The performance data of 2541 lactations of 1001 crossbred cattle, sired by 146 bulls over a period of 30 years maintained at the Livestock Farms of Guru Angad Dev Veterinary and Animal Sciences University (GADVASU), Ludhiana were used for this study. The data on production and reproduction traits were analysed using general linear model procedures based on extremely short ( less than 102 days), short (102-179 days), prolong (483 - 560 days) and extremely prolong (≥ 560 days) lactation lengths on the basis of mean lactation length and its standard deviation. Result: Result indicated that the alteration of lactation lengths affected all important performance traits of crossbred cattle in contemporary as well as in next lactation. The values of 305 days milk yield, lactation milk yield, average fat (%), 305 days fat yield and lactation fat yield of contemporary lactation cycle were higher (P≤0.05) for the extremely prolong lactation length and reduced for shorter lactations. Similar trend was seen for next lactation cycle of the animal having abnormal lactation length in previous lactation cycle for all traits except calf birth weight, whereas days to reach peak yield and fat yield traits were not significantly affected by lactation length classes. The preferred lactation length for crossbred cattle for optimum performance was concluded as 180 to 483 days ranging one standard deviation from mean lactation length, covering more than 72% of population; however, it needs further studies to break it into groups in terms of productive life and economical merits. Farmers should avoid breeding of animal having extremely short and short lactation lengths, as their production and reproductive traits are lower in successive production cycle.

Unraveling the actual background of second litter syndrome in pigs: based on Large White data

Second litter syndrome (SLS) in sows is when fertility performance is lower in the second parity than in the first parity. The causes of SLS have been associated with lactation weight loss, premature first insemination, short lactation length, short weaning to insemination interval, season, and farm of farrowing. There is little known about the genetic background of SLS or if it is a real biological problem or just a statistical issue. Thus, we aimed to evaluate risk factors, investigate genetic background of SLS, and estimate the probability of SLS existing due to the statistical properties of the trait. The records of 246 799 litters (total number born, TNB) from 46 218 Large White sows were used. A total of 15 398 sows had SLS. Two traits were defined: first a binominal trait if a sow had SLS or not (biSLS) and second a continuous trait (Range) created by subtracting the total number of piglets born in the first parity (TNB1) from the piglets born in the second parity (TNB2). Lactation length, farm, and season of the farrowing had significant effects on SLS traits when tested as fixed effects in the genetic model. These effects are farm management-related factors. The age at first insemination and weaning to insemination interval were significant only for other reproduction traits (e.g., TNB1, TNB2, litter weight in parity 1 and 2). The heritability of biSLS was 0.05 (on observed scale), whereas heritability of Range was 0.03. To verify the existence of SLS data with records of 50 000 sows and 9 parities was simulated. The simulations showed that the average expected frequency of SLS across all the parities was 0.49 (±0.05) while the observed frequency in the actual data was 0.46 (±0.04). We compared this to SLS frequencies in 67 farms and only 2 farms had more piglets born in the first parity compared to the second. Therefore, on the individual sow level SLS is likely due to statistical properties of the trait, whereas on the farm level SLS is likely due to farm management. Thus, SLS should not be considered an abnormality nor a syndrome if on average the herd litter size in parity 2 is larger than in parity 1.

238 Reproductive and lactation management for year-round ewe milk production with non-traditional dairy breeds

Abstract The ability of Finnsheep x Dorset meat ewes to achieve high milk yields in short and frequent 73-day lactation periods on the STAR accelerated lambing system in a year-round dairy system was tested together with ewe reproductive success. Ewes (n = 53) were managed in 3 groups and enrolled in a triply replicated (for management group) 3′3 Latin square design (3 pens, 3 lactations, 3 diets). Diets (L-SH, M-SH, H-SH) contained 31.6, 36.3, 40.0% aNDFom and 41.3, 37.2, 31.9% NFC. Milk was recorded at each 2X milking, ewes and lambs weighed weekly. Ewes were bred to lamb with 219-day lambing intervals. To facilitate breeding, progesterone CIDRs were employed for 7 days prior to breeding during increasing day-light period breeding months. Individual lactation curves were fitted to 127 evaluated lactations. Lactation parameters were analyzed with a model including Square Number, Pen and Lactation within Square Number, and Diet, with 3 to 6 ewes in each cell of each Latin Square. Ewes offered the M-SH diet produced more (P = 0.03) milk/d (1.40, 1.58, and 1.37 ± 0.07 kg) and higher (P = 0.02) lactation yields (95.8, 109.6, and 93.0 ± 5.29 kg), compared with ewes offered the L-HS or H-SH diets, respectively. Investigating the effect of breeding season (January, March, June, August, and October) on reproductive success, conception rates ranged between 83.3 and 94.1% and were not affected by breeding season. Litter sizes were lower for matings in March and June (P &amp;lt; 0.05) compared to June, August, and October. Average daily gains of lambs raised artificially ranged between 283 and 328 g ± 11.2 g per day and were significantly higher for January-born lambs than for March born lambs (P &amp;lt; 0.001). Both milk production and reproductive success were high for ewes milked year-round in short and frequent lactations.

Genetic and nongenetic factors associated with lactation length in seasonal-calving, pasture-based dairy cows

Lactation yield estimates standardized to common lactation lengths of 270-d or 305-d equivalents are commonly used in management decision support tools and dairy cow genetic evaluations. The use of such measurements to quantify the (genetic) merit of individual cows fails to penalize cows that do not reach the standardized lactation length, or indeed reward cows that lactate for more than the standardized lactation length. The objective of the present study was to quantify the genetic and nongenetic factors associated with lactation length in seasonal-calving, pasture-based dairy cows. A total of 616,350 lactation length records from 285,598 Irish cows were used. Linear mixed models were used to quantify the associations between lactation length and calving month, parity, age at calving, previous dry period length, calving difficulty score, heterosis, recombination loss, breed, and herd size, as well as to estimate the genetic and residual variance components of lactation length. The median lactation length in the edited data set was 288 d, with 27% of cows achieving lactations of at least 305 d. Relative to cows calving in January, the lactations of cow calving in February, March, or April was, on average, 4.2, 12.7, and 21.9 d shorter, respectively. The lactation length of a first parity cow was, on average, 7.8, 8.6, and 8.4 d shorter than that of second, third, and fourth parity cows, respectively. Norwegian Red and Montbéliarde cows had, on average, a 4.7- and 1.6-d shorter lactation than Holstein-Friesian cows, respectively. The heritability estimate, coefficient of genetic variation, and repeatability estimate of lactation length were 0.02, 1.2%, and 0.04, respectively. Based on the genetic standard deviation for lactation length estimated in the present study (3.3 d), cows ranked in the top 20% for genetic merit for lactation length would be expected to have lactations 9.2 d longer than cows in the bottom 20%, demonstrating exploitable genetic variability. Given the vast array of genetic and nongenetic factors associated with lactation length, an approach which combines improved management practices and selective breeding may be an efficient and effective strategy to lengthen lactations.

Stockpiling by pups and self-sacrifice by their fasting mothers observed in birth to weaning serum metabolomes of Atlantic grey seals

During the uniquely short lactations of true seals, pups acquire a greater proportion of maternal body resources, at a greater rate, than in any other group of mammals. Mothers in many species enter a period of anorexia but must preserve sufficient reserves to fuel hunting and thermoregulation for return to cold seas. Moreover, pups may undergo a period of development after weaning during which they have no maternal care or nutrition. This nutritionally closed system presents a potentially extreme case of conflict between maternal survival and adequate provisioning of offspring, likely presenting strains on their metabolisms. We examined the serum metabolomes of five mother and pup pairs of Atlantic grey seals, Halichoerus grypus, from birth to weaning. Changes with time were particularly evident in pups, with indications of strain in the fat and energy metabolisms of both. Crucially, pups accumulate certain compounds to levels that are dramatically greater than in mothers. These include compounds that pups cannot synthesise themselves, such as pyridoxine/vitamin B6, taurine, some essential amino acids, and a conditionally essential amino acid and its precursor. Fasting mothers therefore appear to mediate stockpiling of critical metabolites in their pups, potentially depleting their own reserves and prompting cessation of lactation.