Dissertations

On this page you will find an overview of dissertations published by PhD students from the Adaptation Physiology Group. When available, you can link through to the full text PDF's, by clicking the project of your interest.

Linking early life conditions to osteochondrosis prevalence in gilts

Koning, D.B. de (2015)

Osteochondrosis (OC) involves the development of necrotic growth cartilage near the surface of a joint and is suggested to be associated with lameness in sows. Development of OC in pigs occurs at young age in a relatively short time frame of several weeks around 10 weeks of age. Due to this time dependency, one may wonder whether there are time dependent effects of factors or conditions associated with OC. The aim of this thesis was to assess whether OC prevalence is associated with conditions encountered in early life such as dietary restriction, floor type, conformation and locomotive characteristics (CLC), natural (auto-) antibodies (N[A]Ab), and carbohydrate levels. Indications for time dependent effects were found for dietary restriction on OC prevalence. This indicated that gilts receiving restricted feeding from 4 to 10 weeks of age and switched to ad libitum feeding until 26 weeks of age had a significantly higher prevalence of OC when compared to gilts receiving restricted feeding after 10 weeks of age. Time dependent effects of floor type were not clearly present, but gilts housed on a deep litter type system using wood shavings after weaning had a higher prevalence of severe OC when compared to gilts kept on a concrete partially slatted floor. Feed with a lower carbohydrate level increased OC prevalence compared to feed with a higher carbohydrate level. We hypothesized that the effects of dietary restriction, floor type, and dietary carbohydrate levels were mediated through loading of the joints either by, respectively, a short rapid increase in weight gain, higher incidence of play behaviors, or by an overall increased body weight.

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A tale too long for a tail too short? : identification of characteristics in pigs related to tail biting and other oral manipulations directed at conspecifics

Ursinus, W.W. (2014)

Tail biting in pigs, i.e. the chewing on and biting in tails of conspecifics, is a multifactorial problem leading to impaired pig welfare and health and economic losses in pig farming. In many countries tail docking is used as a preventive measure, but there is increased societal concern about this practice. Therefore, there is an urgent need to understand, prevent, and reduce tail biting and other
damaging behaviours directed at pen mates. The main aim of this thesis was to identify biological characteristics of barren and enriched housed pigs that relate to their tendency to develop these damaging oral manipulative behaviours. Tail biting started already early in life and pigs that displayed tail biting post-weaning seemed to stem from litters in which tail biting behaviour was already present. The onset of tail biting behaviour was different for individual pigs, and many pigs were not consistently tail biters throughout different phases of life. It was difficult to predict which pigs would develop tail biting based on their individual behaviour.

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The fearful feather pecker : applying the principles to practice to prevent feather pecking in laying hens

Haas, E.N. de (2014)

Billions of laying hens are kept worldwide. Severe feather pecking (SFP) is a behaviour which occurs with a high prevalence on commercial farms. SFP, the pecking and plucking of feathers of another bird, induces pain and stress and can ultimately lead to cannibalism. Moreover, SFP can occur if a bird is unable to cope with fear and stress and is living in an inappropriate environment. SFP thus reduces the welfare of many laying hens worldwide. To prevent SFP it is essential to know the risk factors in its development. To that aim, first, two experimental studies were conducted to gain insight in the principles of SFP, and three on-farm studies were conducted to assess the risk factors of SFP under commercial conditions.

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(Em)pathetic pigs? : the impact of social interactions on welfare, health and productivity

Reimert, I. (2014)

The welfare, health and productivity of intensively raised pigs may be affected by routine management procedures and the physical environment they are housed in, but also by their social environment, i.e. by social interactions between pen mates. In this thesis, the effect of social interactions on pig welfare, health and productivity has been investigated in several ways. On the one hand, a new breeding method based on interactions, i.e. on heritable effects on the performance of pen mates, was investigated. The effect of divergent selection for a relatively positive or negative indirect genetic effect on growth of pen mates on pig behavior and physiology was studied. On the other hand, it was investigated whether pigs can be affected by (the emotional state of) their pen mates on the basis of two social processes, emotional contagion and social support. Pigs selected for a relatively positive indirect genetic effect on the growth of their pen mates seemed less fearful and less stressed in several novelty tests and they had lower leukocyte, lymphocyte and haptoglobin concentrations compared to pigs selected for a relatively negative indirect genetic effect on the growth of their pen mates.

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Sociable swine : indirect genetic effects on growth rate and their effect on behaviour and production of pigs in different environments

Camerlink I. (2014)

Social interactions between pigs can influence their health, welfare, and productivity. The effects of social interactions on individuals are partly genetic, and this genetic effect is known as an Indirect Genetic Effect. IGEs are thus the heritable effects of an individual on the trait values of its social partners, e.g. group mates. Previous research has identified IGE for production traits, which suggests that selection for IGE may contribute to selection response. However, validation through selection experiments is required.

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Assessing welfare of veal calves on farms : measures of behaviour and respiratory disorders and potential ways for welfare improvement

Leruste, H. (2014)

Veal calves are young bovines slaughtered before 8 months of age to produce soft, pale coloured meat. Veal calves are raised indoors in specialised fattening units and receive a diet controlled for iron content consisting mainly of milk replacer with additional solid feed. In Europe, minimal standards for the protection of veal calves are defined in EU directives. These standards however do not necessarily guarantee a sufficient level of animal welfare as each farm has specific conditions for housing and management that may cause welfare issues. There is a demand from part of the consumers to be informed about the level of welfare of farm animals and therefore a need for a scientifically-approved on-farm assessment tool of the welfare state of the animals.

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Molecular effects of fermentation in the gut and its relevance for metabolism and satiety

Haenen, D. (2013)

Dietary fibres, the edible parts of plants that are resistant to digestion and absorption in the human small intestine, were shown to be important in the prevention of obesity and the metabolic syndrome. This association can partially be attributed to a fibre-induced increase in satiety. Dietary fibres can be fermented by bacteria, collectively referred to as the microbiota, in the large intestine (i.e. caecum and colon), resulting in the production of the short-chain fatty acids (SCFAs) acetate, propionate and butyrate. Part of the effect of dietary fibres on satiety is thought to be mediated via the production of SCFAs.

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Fermentation in the gut to prolong satiety: exploring mechanisms by which dietary fibres affect satiety in pigs

Souza da Silva, C. (2013)

Obesity has become a major health problem in humans and companion animals. Although obesity is not common in farm animals, food restriction is often used to maintain low feeding costs and performance of, for instance, pregnant sows and fattening pigs. Food restriction may result in hunger and increased feeding motivation, which are associated with behavioural problems. Knowledge on the regulation of satiety is thus crucial to aid in the control of food intake in humans, and to improve welfare in food-restricted farm animals.

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Piglet birth weight and litter uniformity : importance of pre-mating nutritional and metabolic conditions

Wientjes, J.G.M. (2013)

High piglet birth weights and litter uniformity are important for piglet survival and piglet performance. Within-litter variation in piglet birth weight is the consequence of within-litter variation in early embryo development, which in turn reflects variation in follicle and oocyte development. Insulin-stimulating diets before mating can influence litter development and uniformity, probably through beneficial effects of insulin on IGF-1 and follicle development. The first aim of this thesis, therefore, was to study effects of insulin-stimulating diets during the weaning-to-estrus interval (WEI) on plasma insulin and IGF-1 levels and follicle development, and consequences for embryo, fetal and placental development and uniformity at different stages of pregnancy in sows. Results of this thesis show that plasma insulin levels during WEI can be effectively enhanced by dietary sugars as dextrose and sucrose (high peaks directly after feeding) and starch (enhanced insulin levels at ~4h after feeding) in a dose-dependent manner.

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Foot disorders in dairy cattle : a socio-economic approach to improve dairy cow welfare

Bruijnis, M. (2012)

Foot disorders and the resulting lameness are the most important welfare problem in modern dairy farming. Despite much knowledge about foot disorders and their risk factors,a reduction in the prevalence of foot disorders and lameness has not been achieved. To improve dairy cattle welfare, it is important to increase the awareness of stakeholders. Therefore, the aim of this thesis is to increase the awareness about the problem of foot disorders in dairy farming. A socio-economic approach is used to gain insight into this welfare problem and find strategies to improve dairy cow foot health.

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Effects of hatching time and hatching system on broiler chick development

Ven, L.J.F. van de (2012)

Chicks hatch over a time window of 24-36 hours and are only removed from the hatcher when the majority of the chicks have hatched. Especially for the early hatching chicks this leads to delays in the first feed and water access and consequently negative effects on chick development. In an alternative hatching system, named Patio, the hatching and brooding phase are combined, thereby enabling direct posthatch feed and water access. Environmental conditions in Patio differ from those in hatchers, which may further influence chick quality, physiology, and growth.

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All in good time : dynamics of the bovine estrous cycle investigated with a mathematical model

Boer, M. (2012)

Bovine fertility is subject of extensive research in animal sciences, especially since a decline in dairy cow fertility has been observed during the last decades. One factor is reduced expression of estrous behavior. Fertility is a complex process, regulated by interactions between brain and reproductive organs. The objective of this thesis was to improve insight in the regulation of dairy cow fertility by developing and using a mechanistic mathematical model of the bovine estrous cycle.

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Bruises in Chilean Cattle: Their characterization, occurrence and relation with pre-slaughter conditions.

Strappini, A.C. (2012)

Bruises on cattle carcass affect the quality of the meat and are indicators of poor welfare conditions. According to the literature the occurrence of bruises is related to pre-slaughter conditions, however their contribution is not clear for Chilean cattle. The aim of this thesis was to provide a better understanding of the relationship between pre-slaughter factors and the occurrence of bruises - from loading until slaughter - under Chilean conditions.

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Effects of air quality on chicken health

Lai Thi Lan Huong (2012)

Houses for intensive poultry production likely contain very high concentrations of airborne contaminants that may negatively affect human and animal health. However, very little is known of the relations between concentrations, size, nature and composition of airborne particles on animal health in intensive livestock housing. Also, mechanisms of responses of animals to unhygienic conditions such as airborne particles, and adaptation responses are unknown. It is likely that animals under high pressure for production such as broiler chickens may be affected severely by continuous antigenic stimulation.

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The Second Parity Sows; Causes and consequences of variation in reproductive performance

Hoving, L.L. (2012)

On average, 40% of the sows on a farm are first and second parity sows. Therefore, their reproductive performance has a large impact on farm productivity. Unfortunately, these young sows, especially second parity sows, often experience reproductive problems. This PhD research aimed to alleviate or solve these reproductive problems. The most important conclusions of this thesis are that sow farmers should pay extra attention to growth of sows from first insemination up to first weaning. If sow body development during this period is sufficient, reproductive performance in second parity will improve. In addition, weight loss during first lactation should be controlled and not exceed 10-12% of sow body weight at farrowing.

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Adaptive capacity of rearing hens: effects of early life conditions

Walstra, I. (2011)

The traditional strategy to deal with pathogens in the layer industry is based on monitoring and control methods, primarily aimed at minimizing the risk of infction with the pathogen. The aim of this thesis was to investigate wether the adaptive capacity f layers could be influenced by early life conditions as they may occur in layer practice, as an alternative strategy for improving layer health and disease resistance. The first study investigated whether suboptimal versus optimal invubation, hatch and early rearing conditions could influence the adaptive capacity during infectious challenges with Eimeria and Infectious Bronchitis (IB).

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Learning how to eat like a pig: facilitating vertical information transfer to reduce weaning problems in piglets

Oostindjer, M. (2011)

Piglets in commercial husbandry face a challenge around weaning, because they are weaned abruptly and at a rather young age. Many weanling piglets are poor­ly adapted to ingest solid food, often resulting in a period of underfeeding leading to several health and welfare problems in the immediate postweaning period. The aim of this thesis was to explore whether providing piglets with more op­portunities to learn from their mother about what, how and where to eat incre­ases food intake before and after weaning and consequently can reduce health and welfare problems after weaning.

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Post weaning altrenogest use in sows: follicle growth, endocrine profiles and subsequent fertility

Leeuwen, J.J.J. van (2011)

A severe negative energy balance during first lactation may result in poor reproductive performance in the second litter. Allowing the sow recovery time after weaning by inseminating the sow the second estrus after weaning (skip a heat) improves reproductive performance. Postponing estrus for a shorter period after weaning using daily altrenogest administration has also been found to influence reproductive performance. The aim of this thesis was to develop a better understanding of consequences of altrenogest after weaning for follicle development and subsequent reproductive performance.

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Perinatal development and nutrient utilization n chickens: effects of incubation conditions

Molenaar, R. (2010)

Suboptimal incubation conditions can negatively affect survival and development of chicken embryos. However, physiological mechanisms that may explain these effects, and the long-lasting consequences are largely unknown. Therefore, the first aim of this thesis was to investigate effects of eggshell temperature (EST) and O2 availability during incubation on survival, development, physiology, and nutrient utilization of chicken embryos. The second aim was to investigate long-lasting effects of suboptimal EST on survival and subsequent performance of broiler chickens.

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Talking tails: quantifying the development of tail biting in pigs

Zonderland, J.J. (2010)

Tail biting is an adverse behaviour characterised by manipulation of a pig’s tail by another pig resulting in tail damage and a possible tail biting outbreak. Tail biting is a common problem in the pig husbandry causing economic losses and reduced animal welfare worldwide. To prevent tail biting, the majority of newborn piglets are tail docked, a procedure which is not only painful but generates more and more public concern. This emphasizes the need to prevent the occurrences of tail biting without having to dock a pig’s tail. So far, research focused mainly on the risk factors that can induce tail biting.

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Storage of hatching Eggs; Effects of storage and early incubation conditions on egg characteristics, embryonic development, hatchability, and chick quality

Reijrink, I. (2010)

It is well known that an increase in the storage duration increases incubation duration and decreases hatchability and chick quality. The negative effects of prolonged egg storage (> 7 days) may be caused by changes in the embryo, in the egg characteristics, or by both. The first aim of the current thesis was to investigate which physiological mechanisms are involved in the negative effects of prolonged egg storage on hatchability and chick quality.

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Immunomodulation by diet: Individual differences in sensitivity in layer hens

Adriaansen-Tennekes, R. (2009)

Enhancing relevant immunity of production animals to achieve more robust animals is receiving more and more attention. Several epidemics have hit production animals recently and with devastating onsequences, but enhancing diseases resistance increasingly provides new opportunities. Furthermore, welfare and health of production animals is becoming a more and more consumer driven topic.

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Embryo temperature during incubation: practice and theory

Lourens, A. (2008)

Until recently, all incubator studies were performed using a constant machine temperature (MT). But it is embryo temperature (ET) that is of importance to the embryo, and not MT. In practice, MT is often measured at one location within the incubator, while ET can vary between eggs within an incubator. Furthermore, ET is the result of the balance between heat production (HP) and heat loss, and if HP or heat loss is affected it may have consequences for ET.

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Effects of genetic background and social environment on feather pecking and related behavioural characteristics in laying hens

Uitdehaag, K. (2008)

Woldwide, but especially in Europe, poultry husbandry will undergo significant changes due to the prohibition of both battery cage systems and beak-trimming. In laying hens, these changes will increase the risk of feather pecking. Feather pecking is defined as the non-aggressive pecking towards the plumage of other birds.

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Intermittent suckling and extended lactation: Improving adaptation of piglets to postweaning challenges

Berkeveld, M. (2008)

Conventional weaning of piglets at the young age of 3 to 4 wk is associated with reduced nutrient intake, reduced growth, altered behavioral patterns, and a greater susceptibility to diarrhoea. It is known that an older age at weaning is associated with an improved adaptation to postweaning challenges, e.g. changes in housing and diet. However, extending lactation length is economically undesirable, since this will postpone the establishment of a next pregnancy of the sow.

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Robustness in laying hens : influence of genetic background, environment & early-life experiences

Star, L. (2008)

The aim of the project ‘The genetics of robustness in laying hens’ was to investigate nature and regulation of robustness in laying hens under sub-optimal conditions and the possibility to increase robustness by using animal breeding without loss of production. At the start of the project, a robust animal was defined as ‘an animal under a normal physical condition that has the potential to keep functioning and take short periods to recover under varying environmental conditions’.

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Consequences of intermittent suckling for performance in the pig

Kuller, W.I. (2008)

In Europe, piglets are usually weaned before 4 weeks of age, thus changing abruptly from highly digestible milk to a less digestible starter diet, resulting in reduced feed intake and growth after weaning and sometimes post weaning diarrhea. Intake of a sufficient amount of creep feed during lactation can reduce these post weaning problems, but creep feed consumption is usually low and highly variable.

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Lactational oestrus in sows : follicle growth, hormone profiles and early pregnancy in sows subjected to Intermittent Suckling

Gerritsen, R. (2008)

Weaning of piglets at a relatively young age (3 to 4 weeks) can compromise health and welfare. A possible way to increase piglet welfare is to extend lactation length, but this is economically undesirable due to lactational anoestrus of the sow. Thus, an extension of lactation would reduce the number of litters per sow per year.

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Residual feed intake in young chickens: effects on energy partitioning and immunity

Eerden, E. van (2007)

The continuous selection in farm animals for efficient production and high production levels may have led to animals that are "programmed" to put a lot of resources in production processes, at the expense of resources for maintenance processes, among which the immune system.

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Energy partitioning in dairy cows : effects of lipogenic and glucogenic diets on energy balance, metabolites and reproduction variables in early lactation

Knegsel, A.T.M. van (2007)

Dairy cows experience a negative energy balance (NEB) in early lactation which results from high energy requirements for milk production accompanied by a limited energy intake. Nutrition has been indicated as an important factor in the incidence and severity of NEB and NEB–related metabolic and reproductive disorders, like ketosis and delayed resumption of ovarian activity.

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Cold stress and immunity: do chickens adapt to cold by trading-off immunity for thermoregulation?

Hangalapura, B.N. (2006)

Future animal husbandry aims at enhanced animal welfare, with minimal use of preventive medical treatments. These husbandry conditions will resemble more natural or ecological conditions. Under such farming systems, animals will experience various kinds of stressors such as environmental (e.g. cold, heat, wind), and social stressors (e.g. pecking in chicken, competition for food).

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Heat stress in growing pigs

Huynh, T.T.T. (2005)

Compared to other species of farm animals, pigs are more sensitive to high environmental temperatures, because they cannot sweat and do not pant so well. Furthermore, fast-growing lean pigs generate more heat than their congeners living in the wild. This, in combination with confined housing, makes it difficult for these pigs to regulate their heat balance.

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When to inseminate the cow? : insemination, ovulation and fertilization in dairy cattle

Roelofs, J.B. (2005)

In dairy practice, calving rates after first insemination are often less than 50%. Part of this low percentage might be explained by wrongly timed inseminations. The aim was to establish the relationship between various oestrus characteristics and ovulation time in order to investigate whether these oestrus characteristics could predict ovulation time and to study the consequences of variation in the interval between insemination and ovulation on the success of fertilization and embryonic characteristics.

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Different genetic bases of immune responses in laying hens

Siwek, M. (2005)

Given the growing concerns of consumers regarding the safety of animal-derived foods, it is important to develop effective methods to reduce chronic use of antibiotics and to enhance the effectiveness of vaccine protection by improving, via genetic selection, the innate ability of birds to respond to antigenic challenges. Immune responses to different pathogens follow distinct pathways and resistance to most diseases and pathogens is controlled by polygenes.

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Behavioural motivations and abilities in broilers

Bokkers, E.A.M. (2004)

Broilers are chickens kept commercially under intensive husbandry conditions for poultry meat production. They grow to a slaughterweight of approximately 2.2 kg in 6 weeks. Broilers show a pronounced decrease in behavioural activity during their short life. The aim of this thesis was to gain more insight into the influence of both motivation and ability on behavioural activity in broilers. The distinction between motivation and ability is relevant for the interpretation of behavioural activity in broilers in terms of welfare.

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Long-term performance and behavior of sows fed high levels of non-starch polysaccharides

Van der Peet-Schwering, C.M. (2004)

The main objective of this thesis was to investigate the long-term effects of feeding sows high levels of dietary fermentable non-starch polysaccharides CNSP) (i.e., NSP from sugar beet pulp) restrictedly or ad libitum during gestation or ad libitum during lactation on behavior, reproductive performance, and development in body weight and backfat thickness. During gestation, sows were group-housed.

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Strategies for rearing of rabbit does

Rommers, J.M. (2003)

This thesis describes the effects of different rearing strategies for young rabbit does on body development and reproduction performance. In current rearing, does are often fed to appetite from weaning to first insemination. First insemination is applied when 75 to 80% of mature body weight (BW) is reached, that occurs around 14 to 16 weeks of age. Under current rearing, young does loose significant part of their fat and energy reserves during first lactation.

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Modulation of the chicken immune cell function by dietary polyunsaturated fatty acids

Sijben, J. (2002)

Polyunsaturated fatty acids (PUFA) possess a wide range of biological properties, including immunomodulation. The amount, type, and ratio of dietary PUFA determine the types of fatty acids that are incorporated into immune cell membranes. Consequently, the physiological properties of immune cells and their potential to produce communication molecules, such as eicosanoids, can be modulated.

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Is there a future for the boar? The role of boar stimuli in reproductive processes around estrus in the pig

Langendijk, P. (2001)

This thesis describes several boar stimuli in their potency to elicit estrous behavior and their potency to affect uterine contractility. With different levels of boar stimuli, onset of estrus can be recorded at different time points relative to ovulation, depending on the change in responsiveness of sows to the stimuli. However, the onset of estrus recorded in such ways, as well as the change in responsiveness recorded by using different stimuli to induce estrous behavior, appeared to be bad predictors for the time of ovulation.

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Energy partitioning and reproduction in primiparous sows : effects of dietary energy source.

Brand, H. van den (2000)

As a result of extensive changes in pig husbandry in the last 50 years, nutritional requirements of especially lactating sows nowadays differ strongly from those of sows in the past. Although diets are optimized to meet the requirements, sows still loose body reserves during lactation. Especially in primiparous sows, losses of body reserves during lactation are severe.These sows have not reached their mature body weight and therefore need nutrients for body development.