Padrões de crescimento no cavalo de desporto: aplicação de funções não-lineares

Apresentação oralO conhecimento das taxas de crescimento mais adequadas a cada raça e tipo de utilização é fundamental para criadores e utilizadores. O presente estudo teve como objetivo caracterizar os padrões de crescimento de cavalos de desporto, nascidos e criados numa coudelaria de referência, em França, utilizando funções não lineares. Para o efeito, 72 poldros (39 machos e 33 fêmeas) das raças Hanoveriana e Oldenburgo foram periodicamente pesados e medidos, tendo sido obtidos 1.382 registos para o peso vivo (PV) e altura ao garrote (AG). Os dados foram recolhidos entre o nascimento e os 5 anos de idade, quando os cavalos já estavam em trabalho regular. Inicialmente, foram ajustadas várias funções não-lineares (Brody, Logistic, Gompertz, von Bertalanffy e Richards) utilizando o procedimento NLIN do SAS. Contudo, a equação de Richards y = A(1 – b.exp(-kt))M foi escolhida para a análise posterior por se tratar do modelo que melhor se ajustou às duas variáveis. As taxas de crescimento (GMD, kg/d ou cm/d) foram obtidas a partir da primeira derivada das equações e o efeito do sexo foi também avaliado. O PV médio à idade adulta foi de 623,2±14,1 kg e a altura ao garrote 172,9±1,3 cm. Segundo os modelos obtidos, as proporções (%) do PV adulto aos 6, 12, 24, 36 e 48 meses de idade foram, respetivamente, 39, 55, 74, 84 e 90%. As proporções da AG para as mesmas idades foram 80, 87, 93, 96 e 98%. Não foi observado dimorfismo sexual para a AG. No entanto, os modelos relativos ao PV são diferentes entre poldros e poldras (P<0,0001). As taxas de crescimento obtidas são semelhantes às descritas noutras raças de desporto para um crescimento moderado. O estudo apresentado demonstra que a equação de Richards pode ser utilizada para descrever com precisão o crescimento e o desenvolvimento de cavalos de desporto.Fundação para a Ciência e a Tecnologiainfo:eu-repo/semantics/publishedVersio

Collagen and microvascularization in placentas from young and older mares

Research Areas: Veterinary SciencesIn older mares, increasing collagen fibers (fibrosis) in the endometrium and oviduct predisposes to sub-fertility and infertility. In this study, (i) gene transcription of collagen (qPCR: COL1A1, COL1A2, COL3A1, COL5A1); (ii) total collagen protein (hydroxyproline); (iii) collagen distribution (Picrosirius red staining; polarized light microscopy); and (iv) microvascular density (Periodic acid-Schiff staining), were evaluated in mares’ placenta, and related to mares age, and placenta and neonate weights. Samples were collected from the gravid horn, non-gravid horn, and body of the placenta from younger (n = 7), and older mares (n = 9) of different breeds. Transcripts of COL1A1, COL3A1 and COL5A1, total collagen protein, chorionic plate connective tissue thickness, and microvascularization increased in the gravid horn of older mares’ placentas, compared to the youngest (P < 0.05). Although in other species placenta fibrosis may indicate placental insufficiency and reduced neonate weight, this was not observed here. It appears that older fertile mares, with more parities, may develop a heavier, more vascularized functional placenta with more collagen, throughout a longer gestation, which enables the delivery of heavier foals. Thus, these features might represent morphological and physiological adaptations of older fertile mares’ placentas to provide the appropriate nutrition to the equine fetus.info:eu-repo/semantics/publishedVersio

Portuguese Equidae native breeds: main characteristics, census and demographic parameters

Apresentação em painelThe aim of this study was to summarise the main characteristics of the Portuguese Equidae native breeds. Portugal is a small country from the southwest of Europe with 50 recognised domestic native breeds. Among them there are 6 Equidae breeds, 4 equine (Lusitano, Sorraia, Garrano and Terceira pony) and 2 donkey populations (Miranda and Graciosa). In this review we present an overall census of each population, average body weight, height at withers, skills and uses, dynamics in the studbook and some demographic parameters such as known generations, generation interval and inbreeding. Lusitano horse is the main equine breed, with a close studbook and small census of 3,623 breeding females (half outside Portugal), spread around the globe with more than 30 countries breeding it. The Garrano pony is a small horse from the northwest, with a close studbook, with 1,994 breeding females, 162 stallions, and 435 breeders. Sorraia horse is a primitive southern European breed regarded as an universal genetic resource, very resistant and versatile, managed as a close population since 1937 with only 18 breeders, ~150 breeding females and a total of ~350 animals worldwide. Terceira Pony, from Azores, with an open studbook, was the last to be recognised (2014), with a total of ~100 animals descending from 14 founders. The Miranda donkey from the northeast is a long bay coat animal, with a calm temperament suited for agriculture, milk production and leisure, with a total of 756 females, 60 stallions and 460 breeders. The Graciosa donkey, from Azores, is the most recently recognised donkey breed (2015). With a very small size, a scarce census of 92 dams, of which only 22 are in production, 13 stallions and 63 breeders, are bred for conservation, tourism and milk production. Beside the opportunities for research and conservation programs, all these breeds represent important socio-economic and ecological values, that will enhance the sustainability of Mediterranean production systems.info:eu-repo/semantics/publishedVersio

Growth and conformation changes in the young Lusitano horse: evaluation from birth to one year of age

Nowadays, there is a rising interest in the Lusitano breed as a sport horse. Besides the suggested relationship between growth rate and skeletal development, a better understanding of growing patterns could contribute for an accurate estimation of nutritional requirements in the growing horse. Therefore, the main objective of this study was to evaluate growth and development in Lusitano foals, from birth to one year of age, under extensive management conditions in Portugal. Thirty five foals from three stud farms were monthly weighed and withers height (WH), girth (G) and cannon circumference (CC) were measured. Average age at weaning was 7 mo (209±5d). Quadratic models were best fitted to describe the variation of body weight (BW), G, WH and CC. The effect of farm was significant for BW, G, and CC (P<0.0001), suggesting a management influence. Estimated BW at 7 and 12 mo of age in the three groups, varied between 211.1-253.8 kg and 274.6 327.7 kg, respectively, representing 42.2-50.8 % and 54.9-65.5 % of Lusitano mature BW (500kg). ADG until weaning varied between 0.786-0.888 kg/d, decreasing afterwards in the post-weaning period to 0.258-0.493 kg/d. Weight gain between birth and weaning represents 71.5-80.9 % of total weight gain until 12 mo of age. Estimated values for WH, G and CC at 12 mo of age varied between 135.4-140.9 cm, 145.4-157.5 cm and 16.7-19.0 cm, respectively. These results indicate a similar growth pattern to those described in other sport light breeds when submitted to moderate feeding levels, during the first year of life.vo

Coumestrol and its metabolite in mares' plasma after ingestion of phytoestrogen rich plants : potent endocrine disruptors inducing infertility

Articles in International JournalsPhytoestrogens exist in plants that are present in forages fed to horses. They may compete with 17-β estradiol and influence the estrous cycle. Therefore, the objective was to determine whether coumestrol from clover-mixed pastures is present in mare's plasma after their ingestion (experiment I), and when this phytoestrogen was present in mare's plasma after ingestion (experiment II). The effect of a long-term ingestion of phytoestrogens on estrous cycle disruption was assessed (experiment III; clinical case). Experiment I was carried out in nonpregnant anestrous and cyclic Lusitano mares (n = 14) kept on clover and grass-mixed pastures, and supplemented with concentrate and hay or cereal straw. Blood and feedstuff were obtained from November to March. In experiment II, stabled cyclic Lusitano mares (n = 6) were fed for 14 days with increasing amounts of alfalfa pellets (250 g to 1 kg/day). Sequential blood samples were obtained for 8 hours after feed intake on Day 0 (control) and on Days 13 and 14 (1 kg/day alfalfa pellets). Experiment III mares were fed with a mixture of alfalfa and clover haylage for 5 months (group 1; n = 4) or for 9 months (group 2; n = 12). Estrous cycle was determined on the basis of plasma estradiol (E2), progesterone (P4), and ultrasound (experiment III). Concentrations of phytoestrogen coumestrol and its metabolite methoxycoumestrol were determined by high-performance liquid chromatography coupled with mass spectrometry. Phytoestrogens decreased in pasture from November until March (P < 0.01) (experiment I), but were always detected in mares' plasma. In experiment II, plasma-conjugated forms of coumestrol and methoxycoumestrol were higher on Days 13 and 14 than in control (P < 0.05). The highest concentrations of conjugated form of coumestrol were at 1.5 and 4 hours (P < 0.001), whereas its free forms peaked at 1 and at 3.5 hours after ingestion (P < 0.05). Methoxycoumestrol-conjugated form concentration was the highest at 1.5 and 5 hours (P < 0.001), whereas its free form peaked at 1 hour (P < 0.05) and at 1.5 hours (P < 0.001). Long-term intake of coumestrol caused lack of ovulation, uterine edema, and uterine fluid accumulation (experiment III). Coumestrol and methoxycoumestrol in both forms were higher in group 2 (while still ingesting haylage) than in group 1, after haylage withdrawal (P < 0.001). These data show that in the mare, coumestrol and its metabolite increase in blood after ingestion of estrogenic plants and can influence reproduction in mares as potent endocrine disruptors