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Starting with the achievements of microscopists in the 1880s, attention was directed at the cell's nucleus and its chromosomes as the carriers of the genetic material, to the exclusion of the role of the cytoplasm and all its components (the cell membrane was considered inherently irrelevant). Nuclei were composed of nucleo-proteins. Based on the repetitive tetranucleotide structure hypothesis, first proposed by Hermann Steudel in 1906 and developed by Phoebus Levene in 1931 (Deichmann, 2004), the prevailing conception was that nucleic acids comprised stoichiometric aggregates of nucleotide tetrads. Proteins, being the material of enzymes, were celebrated at the first half of the twentieth century as the essence of life. They seemed to be able to provide the diversity that would be expected of the material of heredity thanks to the large number of known amino acids involved in their composition. Toward the end of the 1940s Fred Singer directly demonstrated the diversity of polypeptide chains, and Wendell Stanley's initial erroneous claim in 1935 that crystallized tobacco mosaic virus was a pure self-replicating protein (a study for which Stanley was awarded the 1946 Nobel Prize) further upheld the centrality of proteins in the deliberations on the nature of the hereditary material (see Deichmann, 2004; Lederberg, 1994). These studies were foreign to genetic analysis and its methodology (see Chapter 1).
Two kinds of nucleic acids were conceived, named after their main source at the time, alkali-stable “thymus” nucleic acid, and alkali-labile “yeast” nucleic acid; corresponding to today's DNA and RNA, respectively.
The involvement of chromosomes as bearers of hereditary continuity had been proposed as early as in the 1880s, when cytologists and embryologists unraveled the processes of fertilization and cell division at mitosis and meiosis. “Only with the recognition that a continuum of structure must be preserved during the development of the individual did heredity assume its modern and more narrow meaning of Vererbung, or transmission” (Churchill, 1987, 364). The dispute over the facts was bitter, but that over the speculations and theories on the meaning of these processes was even more acrimonious. Most daring in his speculations was August Weismann. Weismann's concern with the theoretical problem of deriving totipotent germ cells from a mature organism with differentiated cells led him to argue that germinal cells are transmitted undisturbed from cell to cell in the germ line. He assumed that in the soma cells the chromosomes break down transversely into numerous particles or biophores, and different assortments are farmed out to the cells, which differentiate according to the biophores allocated to them. In the cells of sexually reproducing species chromosomes may often be discerned in a species-specific pattern – there are two of each, one maternal and one paternal, they are diploid. Since the chromosome number in the germ line of all individuals of a species is identical, Weismann further speculated that at the “maturation division” (meiosis) of germ cells, the number of chromosomes is halved – they are haploid (Churchill, 1987).
Johann Gregor Mendel was born in 1822 to a peasant family in a small village in Moravia. Much attention was devoted to his education. As it turned out, Mendel's education was affected by the pansophy teachings of the devout seventeenth-century pedagogue and philosopher Jan Amos Comenius who, in Descartes' words, “too closely combined human science and theology,” yet preached for the threefold virtue of “fullness, order and truth” (Orel, personal communication a). Mendel's interests were in natural history and agriculture. He pursued his studies at the Olomouc University in spite of severe economic difficulties. As he wrote in his curriculum vitae notes in 1850: “It was impossible for him to endure such exertion any further. Therefore, having finished his philosophical studies, he felt himself compelled to enter a station in life that would free him from the bitter struggle for existence. His circumstances decided his vocational choice. He requested and received in the year 1843 admission to the Augustinian monastery of St. Thomas in Brno” (Orel, 1996, 43–44). This was a fortunate choice, primarily because the head of the monastery at the time was the abbot František Cyril Napp, a “scientist, secret freethinker, and an expert in state affairs and economics” (Peaslee and Orel, 2007).
MENDEL IN CONTEXT
Moravia of the first half of the nineteenth century was a prosperous center of industry and agriculture as well as of scientific activity.
The application of biochemical processes as phenotypic markers of Mendelian factors is not new. As early as 1901 the physician Archibald Garrod cooperated with Bateson in collecting “extraordinarily interesting evidence … regarding the condition known as ‘Alkaptonuria’” (Bateson and Saunders, 1902, 133–134). Alkaptonuria was one of several diseases that appeared to be markers of Mendelian factors and were later called by Garrod “inborn errors of metabolism” (Garrod, 1908). Systematic studies of markers of inherent biochemical variability were carried out by J. B. S. Haldane and his associates on the synthesis of anthocyanins that are involved in flower color in various plant species, such as Pelargonium (Haldane, 1954, 52–58). Also in Drosophila notions of the biochemical basis of genetic differences were investigated in studies such as that by Sturtevant (1929) on the eye-color mutant vermilion.
Although many investigators conceived of the role of genes in developmental and biochemical terms, Boris Ephrussi and George Beadle made a breakthrough when they applied the classical methods of developmental mechanics to problems of genetic analysis in Drosophila (Beadle and Ephrussi, 1936). They transplanted the imaginal discs of the eyes from larvae of one genotype into larvae of another type, which enabled them to inspect the transplant's eye color in the host-imago's abdomen. The autonomy or non-autonomy of the transplant's eye color provided an indication of the function of specific genes in the developmental pathways of eye-color pigmentation. Demonstrating the feasibility of that analytic approach, the problem was obviously more biochemical than developmental.
In their classical textbook of 1939 Sturtevant and Beadle noted that:
[l]inkage was first discovered, in the sweet pea, by Bateson and Punnett in 1906. The interpretation they gave is now discredited; but in the same year Lock suggested that, if homologous chromosomes undergo exchanges of materials (as has been suggested by Correns in 1902 on dubious theoretical grounds), then failure of such interchange might account for linkage – i.e., he postulated that linkage is due to genes lying in a single chromosome pair, and that crossing over is due to exchange of materials between homologs.
Sturtevant and Beadle (1962 [1939], 360)
Morgan's concern for the need to distinguish between the production of apparently unrelated and often variable manifold phenotypes of a gene, and of genotypic coupling, the constantly frequent co-inheritance of distinct factors, which had been confounded in the concept of unit character, is exposed in Sturtevant's description of the “moment of insight” many years later, in his A History of Genetics:
In 1909 Castle published diagrams to show the interrelations of genes affecting the color of rabbits. It seems possible now that these diagrams were intended to represent developmental interactions, but they were taken (at Columbia) as an attempt to show the spatial relations in the nucleus. In the latter part of 1911, in conversation with Morgan about this attempt – which we agreed had nothing in its favor – I suddenly realized that the variations in strength of linkage, already attributed by Morgan to differences in the spatial separation of the genes, offered the possibility of determining sequences in the linear dimension of a chromosome.
Thus eventually one may hope to have the whole of biology “explained” in terms of the level below it, and so on right down to the atomic level. And it is the realization that our knowledge on the atomic level is secure which has led to the great influx of physicists and chemists into biology.
Crick (1966, 14)
… the analysis of the hierarchy of living things shows that to reduce this hierarchy to ultimate particles is to wipe out our very sight of it. Such analysis proves this ideal to be both false and destructive.
Polanyi (1968, 1312)
By 1960, with Crick's Central Dogma and the statement that “once the central and unique role of proteins is admitted there seems little point in genes doing anything else” (Crick, 1958, 139), genetics' determinism reached its peak. Jacob and Monod's analysis of “genetic regulatory mechanisms in the synthesis of proteins” further provided the logical extension of Crick's physico-chemical reduction of genetics. In their opening sentences they state that “the ‘structural gene’ accounts for the multiplicity, specificity and genetic stability of protein structures, and it implies that such structures are not controlled by environmental conditions or agents” (Jacob and Monod, 1961, 318). But then, throughout their study they take us through “genes” that do not qualify for that model. This starts with “primary products of the i+ gene,” the repressor which “may be a polyribonucleotide” (Jacob and Monod, 1961, 333; this turned out to be wrong), and ends with the site of the repressor's interaction which they called “operator,” that coordinately regulates the heterocatalytic activity of the “operon” – a battery of structural genes.
The chromosome theory of heredity made the chromosomes, their structure, and their functions major targets of genetic analysis. In 1916 Bridges showed how genetic analysis of exceptional aneuploids (organisms or cells that carry an unbalanced number of chromosomes) also provided analytic tools to gain insight into the mechanism of chromosome pairing and recombination, and into the limited role of the Y-chromosome in development. The part chromosomes play in development was also demonstrated by Blakeslee's trisomics in a study on the Jimson Weed (Chapter 5), and by the studies of Lewis J. Stadler and his students Barbara McClintock and Marcus M. Rhoades, who elaborated on the cytology of maize chromosome aberrations and their phenotypic correlates. Once the efficiency of X-rays in inducing aberrations was demonstrated and genetic experiments were designed to isolate proper chromosome constellations, cytogenetic analysis became a central tool for research, especially in those organisms whose chromosomes were large enough or otherwise easy to observe.
EUPLOIDY AND SEX DETERMINATION
Boveri's studies of the development of aneuploid sea urchin embryos indicated the importance of a complete and balanced set of chromosomes for development (Chapter 5). The importance of a complete and balanced set of chromosomes was also demonstrated by the normal development of triploid zygotes of organisms that are otherwise diploid, such as triploid Drosophila females.
Many plant species can be shown to be ploidly-related to each other. This is especially significant in cultivated plants, where over the millennia breeders selected (or produced) polyploids.
The subject of this book is genetic analysis. I have been involved in genetic analysis for over a half century, first in active experimental research and later doing research on the history and philosophy of genetics.
In 1965, the centenary of Mendel's presentation to the Natural History Society in Brno, two books were published with almost identical titles by two leading geneticists of that time: Alfred H. Sturtevant's A History of Genetics (1965) and Leslie C. Dunn's A Short History of Genetics (1965). Sturtevant's preface was very brief and succinct: “The publication of Mendel's paper of 1866 is the outstanding event in the history of genetics; but … the paper was overlooked until 1900, when it was found. Its importance was then at once widely recognized. These facts make the selection of topics for the early chapters of this book almost automatic” (Sturtevant, 1965, vii). I will discuss this notion at some length in later chapters. Dunn's approach was more reflective; he focused on the role and significance of the history of science. With respect to the history of genetics, Dunn noted:
One of the interesting things about the history of genetics is that a few relatively simple ideas, stated clearly and tested by easily comprehended breeding experiments brought about a fundamental transformation of views about heredity, reproduction, evolution and the structure of living matter. It was chiefly the elucidation of the theory of the gene and its extension to the physical basis of heredity and to the causes of evolutionary changes in populations which gave genetics its unified character.
In their short paper of April 25, 1953, Watson and Crick introduced their model of the structure of DNA. Although this is a presentation of a physico-chemical model, and the authors make “the usual chemical assumptions,” they emphasize that “The structure has novel features which are of considerable biological interest.”
The structure has two helical chains each coiled round the same axis. … The novel feature of the structure is the manner in which the two chains are held together by purine and pyrimidine bases. … They are joined together in pairs … adenine (purine) with thymine (pyrimidine), and guanine (purine) with cytosine (pyrimidine). … The sequence of bases on a single chain does not appear to be restricted in any way. However, if only specific pairs of bases can be formed, it follows that if the sequence of bases on one chain is given, then the sequence on the other chain is automatically determined.
Watson and Crick (1953b)
The authors notice that the model appears to be “roughly compatible with the experimental data, but it must be regarded as unproven until it has been checked against more exact results.” Nevertheless, in the final paragraph they state that it “has not escaped our notice that the specific pairing we have postulated immediately suggests a possible copying mechanism for the genetic material” (Watson and Crick, 1953b).
For Mendel the function of hereditary factors was a secondary issue. When he encountered the phenomena of dominating and recessivity he referred to them simply as facts that must be considered when dealing with the transmission of the factors:
Although the intermediate form of some of the more striking traits … is indeed nearly always seen, in other cases one of the two parental traits is so predominant that it is difficult, or quite impossible, to detect the other in the hybrid. … This is of great importance to the definition and classification of the forms in which the offspring of hybrids appear.
Mendel, in Stern and Sherwood (1966, 9, italics added)
Mendel further emphasized that although “some of the more striking traits” show intermediate forms in hybrids, he deliberately selected for his experiments such traits that could be discerned qualitatively, so that he would be able to classify his data into binary categories (Falk, 2001a).
Not so for de Vries, for whom dominance was the clue to understanding function and development. He introduced his 1900 paper Das Spaltungsgesetz der Bastarde in terms of function rather than transmission:
According to pangenesis the total character of a plant is built up of distinct units. These so-called elements of the species, or its elementary characters, are conceived of as tied to bearers of matter, a special form of material bearer corresponding to each individual character. Like chemical molecules, these elements have no transitional stages between them.
de Vries, in Stern and Sherwood (1966, 107, italics added)
PIGCAS (Attitudes, practices and state of the art regarding piglet castration in Europe) is to our knowledge the first project that has focused on castration practice across European countries (European Union minus Bulgaria, Malta and Romania, plus Norway and Switzerland). About 250 million pigs are slaughtered in Europe each year. Of the 125 million male pigs, approximately 20% are left entire, less than 3% are castrated with anaesthesia and the rest is castrated without anaesthesia. The study identified large variations in castration procedures, both within and between countries. In females, castration is very rare, but is practiced without anaesthesia in special breeds/production systems in some of the southern countries.
Streptozotocin-induced diabetes mellitus (STZ-DM) in rats is a model of type 1 diabetes, which is commonly used to study diabetes, but differs from human diabetic pathophysiology in its insulin resistance. An STZ-DM rat can be administered five times the dose of insulin compared to that of a diabetic patient. Thus, attaining normoglycaemia in STZ-DM rats with insulin injections is complicated, and it involves an obvious risk of overdosing before getting a response. This study was designed to investigate whether suboptimal treatment with long-acting insulin restores insulin sensitivity in the STZ-DM rat, and thus an approach to more closely mimic the human condition. Male Sprague-Dawley rats were made diabetic by means of a single intravenous injection of STZ (55 mg/kg body weight (BW)), resulting in an increase in blood glucose (BG) from 6.5 ± 0.2 to 22.5 ± 1.0 mmol/l (P ⩽ 0.05) within 24 h. After treating the STZ-DM rats with vehicle for 14 days, BG was 26.1 ± 1.1 mmol/l, and the response to a single injection of fast-acting insulin (Humalog, 5 IE/kg BW) was a 23% reduction in BG. Thereafter, the rats were treated daily with a suboptimal dose of long-acting insulin for a total of 7 days (Insulatard, 5 IE/kg per day), which resulted in a BG level of 19.4 ± 2.7. The response to fast-acting insulin after the suboptimal treatment was a 61% reduction in BG. Thereafter, the animals were vehicle-treated for another 7 days, which resulted in a response to fast-acting insulin similar to the initial values (−34%). Furthermore, the group treated with suboptimal doses of long-acting insulin had a longer duration of the reduction in BG (150 min, as opposed to 90 min in the vehicle-treated groups). We conclude that the development of a decreased insulin response occurs rapidly within the first 2 weeks after the onset of diabetes in STZ-DM rats. This leads to a brief and significantly reduced decrease in BG when fast-acting insulin is administered. The insulin response is increased by treatment with suboptimal doses of long-acting insulin, but rapidly decreases again when treatment is withdrawn. Regular administration of suboptimal insulin doses may provide an approach to eliminate the effects of a lowered insulin response.
Adipocyte size and number are correlated with fat deposition, which is of major concern to human health and pork producers. To identify quantitative trait loci (QTL) for adipocyte size and number in pigs, a total of 341 F2 animals at 240 days in a White Duroc × Erhualian cross were measured for the area, perimeters, volume and number of adipocyte in abdominal fat. A genome scan was performed on these animals and their parents and grandparents with 183 microsatellite markers spanning the pig genome. Five chromosomal regions showed effects on the traits measured, predominantly on adipocyte size, on pig chromosome (SSC) 1, 4, 7 and 9. Neither of these QTL has been reported before this study. The QTL for adipocyte size detected in this study perfectly correspond to the previously reported QTL for fatness traits on SSC1, 4 and 7. The most significant association was evidenced at 58 cM on SSC7. At the locus, the favorable allele decreasing adipocyte size was unusually originated from the obese Erhualian breed. Only a suggestive QTL was detected for adipocyte number on SSC9. The results shed new lights on the understanding of the genetic basis of fatness traits in pigs.
Postnatal muscle growth is dependent on satellite cell (SC) proliferation, differentiation and fusion to increase the DNA content of existing muscle fibres and thereby the capacity to synthesize protein. The purpose of the present study was to examine the ability of isolated SCs from low, medium and high weaning weight litter mates of pigs to proliferate and differentiate, and to affect protein synthesis and degradation after fusion into myotubes. At 6 weeks of age, SCs from the lowest weight (LW), medium weight (MW) and highest weight (HW) female pigs within eight litters were isolated. Thereby, eight cultures of SCs were established for each of the three weight groups within litter, representing three groups of SCs from pigs exhibiting differences in postnatal muscle growth performance. Proliferation was estimated as the number of viable cells at different time points after seeding. SC differentiation was evaluated by measuring the activity of the muscle-specific enzyme, creatine phosphokinase, and protein synthesis and degradation were measured by incorporation and release of 3H-tyrosine, respectively. A tendency towards a difference in proliferation between SC cultures was found (P = 0.09). This was evident as the number of viable cells at day 3 was lower in cultures from LW pigs than from HW (P < 0.05) and MW (P < 0.01) pigs. Differentiation was significantly different between cultures (P < 0.05). There was a significant difference between LW and MW cultures at 72 h (P < 0.05), and a tendency towards a difference between LW and HW cultures at 45 h (P = 0.07). Protein synthesis per μg protein or per μg DNA did not differ among SC cultures from LW, MW and HW pigs. Neither did protein degradation rate differ significantly among SC cultures from LW, MW and HW pigs. Overall, the results show that SCs from LW pigs seem to proliferate and differentiate at a slower rate than SCs from MW and HW pigs. The results found in this study show no difference in the ability of SCs to affect protein synthesis or degradation between SCs from litter mates exhibiting different growth rates in vivo.
Probiotics such as lactic acid bacteria directly influence the host’s health and have beneficial effects such as decreasing the number of enteric pathogens, regulating intestinal immune responses and preventing diseases. Among domestic animals, probiotics have been expected to be an alternative to antibiotics added in the diet; and fermented liquid diet (FLD) containing probiotics has great potential as a diet for reducing the use of antibiotics. In this study, we evaluated the immunomodulatory effects of FLD, prepared using Lactobacillus plantarum LQ80 (LQ80), on the immune response of weaning pigs. Ten weaning piglets were divided into two groups and were fed the FLD (n = 5) or a non-fermented liquid diet (NFLD) (n = 5) for 28 days. At the end of the experiment, the total immunoglobulin M (IgM) and immunoglobulin G (IgG) levels in the sera of the FLD-fed piglets were significantly higher than those of the NFLD-fed piglets (P < 0.05). In contrast, the total immunoglobulin A (IgA) levels in the feces and saliva were not significantly affected by FLD feeding. However, the mean fecal IgA levels of FLD-fed piglets at day 28 were higher than those at 14 and 21 days (P < 0.05). Blood cells from the FLD-fed piglets showed a low level of interferon-γ secretion and mitogen-induced proliferation compared to that of the NFLD-fed piglets. Furthermore, the levels of interluekin-8 and tumor necrosis factor-α, which are proinflammatory cytokines, in the blood cells of the FLD-fed piglets were lower than those of the NFLD-fed piglets (P < 0.05). In conclusion, the FLD used in this study could alter the immune responses of weaning piglets by stimulation of the systemic or mucosal antibody response, without unnecessary inflammatory reactions. This indicates, that the FLD feed prepared with the use of LQ80 may be a candidate feed, with regard to enhancing immune responses and preventing diseases in weaning piglets.
Stimuli from a prospective mate increase the secretion of luteinising hormone (LH) in sheep. This ‘male effect’ in ewes and ‘female effect’ effect in rams is predominantly mediated by olfactory signals, though it is thought that non-olfactory signals play synergistic or substitutive roles. In this study, we tested whether exposure to visual or audio–visual stimuli from a prospective mate would stimulate an increase in LH secretion in ewes (Experiment 1) and rams (Experiment 2). In Experiment 1, groups of eight Merino ewes were exposed to one of three stimuli midway through a frequent blood-sampling regimen: full ram contact, still images of rams, a video of ewes and rams mating. Control ewes (n = 8) were completely isolated from rams. Exposure to still images of rams appeared to stimulate an increase in mean LH concentrations (P < 0.05) and tended to increase LH pulse frequency (P < 0.1), but the response was significantly smaller than that observed in ewes exposed to rams (P < 0.01). Audio–visual stimuli had no effect on any parameters of LH secretion (P > 0.1). In Experiment 2, Merino rams were allocated to either an Exposure (n = 7) or a Control (n = 7) group. Exposure rams underwent two exposure periods midway through a frequent blood-sampling regimen; exposure to still images of ewes and audio recorded during mating of ewes and rams (audio–visual exposure); exposure to oestrous ewes (ewe exposure). Control rams were sampled at the same frequency but remained isolated from ewe stimuli. Exposure of rams to the audio–visual stimuli did not affect any parameters of LH secretion (P > 0.1). In contrast, exposure to oestrous ewes increased LH pulse frequency (P < 0.05) and advanced the onset of the next LH pulse (P < 0.05). In conclusion, visual signals appear to be involved in eliciting the neuroendocrine response of ewes to rams and are of greater importance to this phenomenon in ewes (male effect) than rams (female effect). However, overall the visual and audio–visual signals used in this study were far less effective than stimulus animals, suggesting that these stimuli are less important than olfactory signals, or a combination of olfactory and audio–visual signals.
Ruminant fat is often perceived as having a negative impact on human health; however, the composition of the fat is under complex biochemical control and can be improved through strategic manipulation of the animal’s diet. There were two major objectives of this study, namely (i) to develop and validate a primary bovine intramuscular adipocyte cell line and (ii) to examine the effect of eicosapentaenoic acid (EPA) on the transcriptional regulation of Δ-9 desaturasein vitro using the novel cell line. Intramuscular adipose tissue was obtained from the Musculus longissimus thoracis of a beef heifer. Mature adipocytes were isolated and cultured, and subsequently harvested and evaluated for lipid accumulation and the expression of genes regulating key functional adipocyte protein markers at passages 10, 20 and 30. Isolated cells were shown to accumulate lipid in culture over time. Fatty acid analysis by gas chromatography was carried out at passage 30. Thirteen fatty acids ranging from tetradecanoic acid (C14:0) to the polyunsaturated fatty acid, docosahexaenoic acid (C22:6), were easily detected and measured. High-quality total RNA was isolated from adipocytes and the expression of peroxisome proliferator-activated receptor-γ, fatty acid synthase, fatty acid-binding protein-4, adipocyte lipid-binding protein, CD36, Δ-9 desaturase, sterol regulatory element-binding protein (SREBP), microsomal triglyceride transfer protein and leptin genes were identified by reverse transcriptase-PCR and sequence analysis. Expression of the negative control, liver-specific hepatocyte nuclear factor-1alpha, was not detected. Adipocytes were subsequently incubated in medium containing 0, 50 or 100 μM EPA for 24 h. Increasing the EPA concentration of the culture media led to a linear increase in adipocyte EPA concentration (P < 0.01). Expression of Δ-9 desaturase mRNA was decreased five- and seven-fold, respectively, following 50 and 100 μM EPA incubation compared to the control. Gene expression of SREBP-1c was decreased by 6- and 18-fold in cells supplemented with 50 and 100 μM EPA, respectively, compared to the control. Regression analysis showed a negative linear relationship between EPA concentration and the gene expression of both Δ-9 desaturase (P < 0.001) and SREBP-1c (P < 0.001), while a significant positive relationship was observed between Δ-9 desaturase and SREBP-1c gene expression (P < 0.001). This is the first report demonstrating that EPA treatment of bovine intramuscular adipocyte cells decreased gene expression of both Δ-9 desaturase and SREBP-1cin vitro. The bovine adipocyte cell line developed here is an important resource for future studies facilitating less-expensive, rapid screening of research hypotheses and circumventing the limitations associated with the use of experimental animals including cost, inter-animal variation, pre-experimental management and ethics.
The objective of the present study was to determine the effect of plane of nutrition in early pregnancy (EP) and mid-pregnancy (MP), on the productive performance of 1- and 2-year-old ewes and their offspring. Over 2 successive years, between days 0 and 39 after synchronized mating (EP), 1- (n = 117) and 2- (n = 52) year-old ewes were allowed 60% (low, L-EP), 100% (medium, M-EP) or 200% (high, H-EP) of requirements for maintenance (M). Between days 40 and 90 (MP), 1-year-old ewes were allowed 140% (M-MP) or 200% (H-MP), while 2-year-old ewes were allowed 80% (M-MP) or 140% (H-MP) of their M requirement. After day 90, all ewes were fed to meet requirements for late pregnancy. Increasing the plane of nutrition between days 0 and 39 resulted in increases in live weight (LW) (P < 0.001) and body condition score (BCS) (P < 0.001) during the EP period (H-EP > M-EP > L-EP), differences that in 1-year-old ewes were sustained to lambing (P < 0.05). On day 42 of gestation H-EP ewes had lower plasma progesterone concentrations than L-EP or M-EP ewes in 1- (P < 0.01) and 2- (P < 0.001) year olds. This was concomitant with diet H-EP tending to reduce the number of lambs born per ewe in both age groups (P = 0.06 and 0.07, respectively). Foetuses from 1-year-old L-EP ewes had smaller cranial (P < 0.01) and abdominal (P < 0.05) diameters at day 53 of gestation, with H-EP lambs tending to be heaviest at birth (P = 0.07). Similar findings were recorded for 2-year-old ewes. One-year-old ewes offered diet L-EP presented negative maternal behaviours more frequently (P < 0.05), while the incidence of lamb mortality at 6 weeks tended to be greater for L-EP lambs (P = 0.07). In MP, 1-year-old ewes offered diet M-MP were associated with foetuses with bigger abdominal diameters at day 78 (P < 0.05). However, there were no differences in lamb weight or size at term (P > 0.05). These ewes exhibited more positive maternal behaviours (e.g. increased grooming frequency and duration; P < 0.05) than ewes offered diet H-MP, and their offspring were more successful in suckling (P < 0.05). Results suggest that in young ewes, a temporary nutrient restriction in EP resulted in increased prolificacy. However, ewes and their offspring were lighter at birth and ewe maternal behaviour was poorer, resulting in increased lamb mortality. In MP, a medium plane of nutrition offered to 1-year-old ewes led to improved maternal and offspring behaviour.
Studies of bruises, as detected on carcasses at the slaughterhouse, may provide useful information about the traumatic situations the animals endure during the pre-slaughter period. In this paper, we review scientific data on the prevalence, risk factors and estimation of the age of bruises in beef cattle. Risk factors such as animal characteristics, transport conditions, stocking density, livestock auction and handling of the animals are discussed. Investigation of the age of bruises could provide information on when in the meat chain bruises occur and, could help to pinpoint where preventive measures should be taken, from the stage of collecting the animals on the farm until slaughter. We review the methods available to assess the age of the bruises; data on human forensic research are also included. The feasibility to identify traumatic episodes during the pre-slaughter period, in order to improve animal welfare is discussed.