Male Foals Research Articles

A comparison of the carcass and meat quality of Martina Franca donkey foals aged 8 or 12 months

The effects of slaughter age (8 vs 12months) were investigated on meat and carcass quality obtained from Martina Franca donkey foals. Sixteen male foals were used, eight were slaughtered at 8months of age with a mean (±s.e.) final body weight of 101±18kg and the remaining 8 foals slaughtered at 12months of age with a mean final body weight of 122±13kg.Carcass weight and dressing percentage were higher (P<0.05) in older foals. Shear force value was lower (P<0.05) in donkeys slaughtered at 8months of age (54.03N) compared to the same muscle Longissimus Thoracis et Lumborum (LTL) collected in older animals (62.66N). Muscle glycogen content was higher (P<0.05) in foals slaughtered at 12months of age. Donkey foal meat showed an interesting content of essential amino acids and a notable percentage of unsaturated fatty acids in both groups of animals, giving a high nutritional value to this alternative red meat.

Left-Sided Ovulation Favors More Male Foals Than Right-Sided Ovulation in Thoroughbred Mares

The side of pregnancy has been observed to impact the sex of offspring in different species of mammals. Accordingly, the present study was conducted to investigate the distribution of male and female foals in the left and right ovaries in Thoroughbred mares. To do so, data associated with sex of foals, side of ovulation, stallion ID, and age and parity of mares at conception were collected from four horse centers. In total, data consisted of 238 birth records from 238 dams and 23 sires. Data were analyzed using univariable and multivariable logistic regression analyses. The incidence of left and right ovulations were 51.3% (122/238) and 48.7% (116/238), respectively, which were not different (P > .05). Secondary sex ratio (SSR; the proportion of male foals at birth) in nulliparous mares (29/83, 34.9%) was lower than that in parous mares (82/155, 52.9%; adjusted odds ratio, 0.388; P = .005). Moreover, conception of oocyte ovulated from the left ovary resulted in higher proportion of males (70/122, 57.4%) than conception of oocyte ovulated from the right ovary (41/116, 35.3%; adjusted odds ratio, 3.636; P < .0001). Secondary sex ratio of right-sided ovulation was lower than the expected 50.0% SSR (odds ratio, 0.547; P = .026), but SSR of left-sided ovulation and overall SSR (111/238, 46.6%) did not differ from the expected 50.0% SSR (P > .05). In conclusion, the present study showed dissimilar distribution of male and female foals for left and right ovulations in ovaries of Thoroughbred mares. Moreover, the results indicated the effect of parity on the proportion of male foals in equine.

Effect of Sire-Associated Factors on Secondary Sex Ratio of Offspring in Equine

The objective of the present study was to evaluate the effect of breed of stallion and individual stallion on secondary sex ratio (SSR; the proportion of male foals at birth). Data associated with the sex of foals and the sire, as well as the breed and age of sire were retrieved from the database of the Equestrian Federation of the Islamic Republic of Iran. In total, data consisted of 4,491 birth records from 92 stallions. Stallions were from three breeds of Arabian, Thoroughbred, and Akhal-Teke. Data were analyzed using univariable and multivariable logistic regression. Proportion of colts was 63.0% (427/678), 46.1% (1,545/3,355), and 53.9% (247/458) in Arabian, Thoroughbred, and Akhal-Teke stallions, respectively. In Arabian stallions, SSR was skewed toward males (P < .0001; odds ratio, 1.701), whereas in Thoroughbred stallions, it was skewed toward females (P = .001; odds ratio, 0.853). Secondary sex ratio was not skewed in Akhal-Teke stallions (P > .05). Secondary sex ratio in Thoroughbred stallions was lower than that in Arabian (P < .0001; adjusted odds ratio, 1.983) and Akhal-Teke (P = .010; adjusted odds ratio, 1.527) stallions, but SSR did not differ between Arabian and Akhal-Teke stallions (P > .05). There was the effect of individual stallion on SSR in Arabian and Thoroughbred breeds (P < .0001) but not in Akhal-Teke breed (P > .05). In conclusion, the present study showed the effect of breed of stallion and stallion itself on sex ratio of foals.

Inter-birth interval in zebras is longer following the birth of male foals than after female foals

Mammalian reproductive rates vary among individuals for physiological and environmental reasons. This study aims to determine reproductive rates from an individually monitored population of wild Plains zebras Equus quagga, and to assess the sources of variability in inter-birth intervals. The animals were monitored, where possible, every six months from 2004 to 2011. Thirty nine intervals corresponding to 65 births in 26 mares were identified, using direct observations and faecal steroid monitoring. Mean foaling rate of the population is 0.74 foal/year, and comparable with the literature. There was no significant effect of mother’s age, nor of the season of previous birth on the length of inter-birth intervals. Inter-birth interval was significantly longer when the first foal was a male. This finding indicates that additional costs of having a son may delay future reproduction and thus reduce the total number of offspring a mare can have during her lifetime. Individually-based data provide critical information on the determinants of reproductive rates, and are therefore a key to understanding the causes of variations in life-history traits.

Further evidence for sex differences in suckling behaviour of captive plains zebra foals

Sex differences in suckling behaviour could be explained either by different maternal investment or by different behaviour of young. Previously, we found sex differences in rejection and termination of suckling bouts in captive plains zebras (Equus burchellii). In this study, we analysed the length of suckling bout interruptions and unsuccessful subsequent attempts which followed a successful suckling bout in plains zebra foals at Dvůr Kralove Zoo. When a suckling bout was interrupted, male foals resumed the bout sooner than female foals. The probability of a subsequent attempt decreased with increasing age in female foals but did not change in male foals. These results demonstrate higher effort in suckling interest by male foals, who tried to suckle more than female foals. Although we found sex bias in the effort to suckle, which suggested higher parent–offspring conflict in male offspring, we cannot omit a sex bias in milk supply by the mother.

Suckling behavior in captive plains zebra (Equus burchellii): Sex differences in foal behavior1

We predicted that the proportion of suckling attempts rejected and terminated by the mother would be greater for female foals than male foals, based on parent offspring conflict theory and on the assumption that throughout the study, all zebra mothers were in good condition because of captivity. We presumed that an increasing rate of suckling terminated or rejected by a mother would indicate a decreasing effort by the mother to invest in her offspring. We observed foals of captive plains zebras at the Dvůr Králové Zoo, Czech Republic. We found that the probability of successful suckling tended (slope = 0.0016; Z = 1.78; P = 0.074) to increase with increasing age of the female foals, but decreased (slope = -0.0018; Z = -2.51; P = 0.012) with increasing age of the male foals. The proportion of suckling bouts terminated by the mother decreased (slope = -0.0077; Z = -4.27; P < 0.0001) with increasing age of the female foals, but not the male foals (slope = -0.0005; Z = -0.34; P = 0.732). Our results indicate that conflict between mothers and female foals was less than that between mothers and male foals. The observed sex differences in termination and rejection of suckling bouts could be explained by the different behavior of the male and female foals, or by the selective maternal investment. Finally, we revealed no significant effect of herdmates on suckling behavior.

Efeitos do processamento da alfafa e da adição de óleo de soja sobre a digestibilidade total da dieta de eqüinos

Avaliou-se o efeito do processamento do feno de alfafa (Medicago sativa L.) e da adição de óleo de soja em dietas sobre a digestibilidade total de matéria seca, matéria orgânica, proteína bruta, extrato etéreo, fibra em detergente neutro e fibra em detergente ácido em eqüinos. Utilizaram-se quatro potros machos, sem raça definida, com aproximadamente 14 meses de idade e 197,25 kg, em delineamento quadrado latino (4 × 4) e em arranjo fatorial (2 × 2), composto de duas formas de fenação da alfafa (em cubos ou em ramas) e da adição ou não de óleo de soja em dietas contendo concentrado comercial na forma de péletes. A digestibilidade dos nutrientes foi determinada pelo método de coleta total de fezes durante três dias. A adição de óleo de soja refinado aumentou a digestibilidade total de matéria seca, matéria orgânica, extrato de etéreo e fibra em detergente neutro. A fenação da alfafa em cubos aumentou a digestibilidade total da proteína bruta, fibra em detergente neutro e da fibra em detergente ácido. A adição de óleo de soja nas dietas avaliadas foi um modo prático e seguro de aumentar a densidade calórica sem reduzir a digestibilidade dos macronutrientes orgânicos. O processamento da alfafa na forma de cubos melhorou a digestibilidade total da proteína bruta, fibra em detergente e fibra em detergente ácido da dieta em eqüinos.

Some phenotypic and genetic parameters of racing performance in Arabian horses

Summary: The aim of this study was to investigate the factors affecting racing performance and to estimate the heritability of racing performance in Arabian horses. In this study the records were obtained from 6203 races of 616 male foals of 37 stallions racing at open races in different race tracks in Turkey during the years of 1991-2000. The least squares mean of racing time was found to be 176.29±0.95 seconds and there were significant differences (p<0.001) in racing years, racing distances, racing groups and race tracks. The estimated mean value for the amount of earning was 15660.6±556.7 $ (USA). The effect of mare age, year, distance, racing group, race tracks and foal age on the earning were significant (p<0.05; p<0.001). There were statistically significant differences among mean value of speed (m/second) for all of the investigated factors and the variance among stallions was found to be significant. The heritability of mean speed was estimated as 0.170±0.001 according to paternal half sib correlation method, the heritability according to the mean amount of earnings was 0.46±0.15. In this study heritability for racing performance was found to be moderate and therefore it is concluded that this character was improved by selection.

Sex Preferences in Jeju Pony Foals (Equus caballus) for Mutual Grooming and Play-Fighting Behaviors

We investigated mutual grooming by Jeju pony (Equus caballus) foals to determine whether male foals preferentially interact with potential future sexual partners or competitors. We predicted that relative to female foals, male foals would exchange grooming more frequently with young mares and that in general, foals would mutually groom more frequently with the opposite sex rather than the same sex. Observing 53 foals between April and October 1998, we recorded 113 mutual grooming events. Male foals exchanged grooming with yearling mares more frequently than with their mother, while female foals exchanged grooming with their mother more frequently than with yearling mares. Contrary to the prediction, foals were not more likely to mutually groom with a foal of the opposite sex than with a foal of the same sex. In our study, 21 instances of play-fighting behavior followed mutual grooming between peers. Relative to intersexual grooming events, play-fighting was more likely to follow intrasexual mutual grooming, and male foals were much more likely to play fight than female foals. These results provide evidence that Jeju pony foals develop and maintain social relationships at the earliest stage of their lives. We suggest that early social experiences might influence social bonding later when the male foal begins to form a harem after separation from its mother.

Molecular and cytogenetic paternity testing of a male offspring of a hinny

An alleged male foal of a female mule, whose sire and grandparents were unknown, was identified for its pedigree. Parentage testing was conducted by comparing polymorphism of 12 microsatellite DNA sites and mitochondrial D-loop sequences of the male foal and the female mule. Both the sequence analysis of species-specific DNA fragments and a cytogenetic analysis were performed to identify the species of the foal and its parents. The results showed that the alleged female mule is actually a hinny, and the male foal, which possesses 62 chromosomes, qualifies as an offspring of the female hinny and a jack donkey.

Avaliação da silagem de grãos úmidos de milho na alimentação de eqüinos em crescimento: valor nutricional e desempenho

Dois experimentos foram conduzidos com o objetivo de avaliar a utilização da silagem de grãos úmidos de milho (SGUM) para eqüinos em crescimento. No experimento I, foram utilizados 12 potros machos, com 11 meses de idade, peso vivo médio de 232,17±10,22 kg, em um ensaio de digestibilidade, para determinar o valor nutritivo da SGUM. Foram utilizadas duas dietas, uma referência e uma teste, na qual a SGUM substituiu 25% da matéria seca da dieta referência. Utilizou-se o método da coleta total de fezes para a determinação dos coeficientes de digestibilidade aparente dos nutrientes. Os teores de matéria seca digestível, proteína digestível, fibra digestível, fibra em detergente neutro digestível, fibra em detergente ácido digestível, amido digestível e energia digestível com base na matéria seca, foram respectivamente, 86,66%; 4,94%; 0,83%; 3,56%; 1,28%; 70,63% e 3.667 kcal/kg. No experimento II, foram utilizados 16 potros machos, com 12 meses de idade, peso vivo médio de 238,67±18,85 kg. O delineamento experimental utilizado foi inteiramente casualizado, com quatro repetições e um animal por unidade experimental, por um período de 90 dias. Os tratamentos consistiram de uma ração testemunha e três níveis de substituição, de 35, 65 e 100% do grão de milho seco por SGUM, formulados de tal forma a serem isoprotéicas e isoenergéticas. Não se verificaram efeitos das dietas sobre o ganho diário de peso vivo, aumento da altura na cernelha, aumento do perímetro torácico e aumento dos perímetros de joelho e canela pelos potros. Os resultados obtidos indicam que a silagem de grãos úmidos de milho constitui-se em uma alternativa viável de substituição do milho grão seco em rações para eqüinos em crescimento.

On some normal hematological values in foals and arabian horses at different ages

Hematological values of twenty normal male foals at 1-6 months , 7-12 months and sixty Arabian horses at 1-5 years old were estimated respectively. Red blood cell count ( RBCS), hemoglobin concentration (Hb), packed cell volume (PCV% ), mean corpuscular volume (MCV) ; mean corpuscular hemoglobin (MCH), mean corpuscular hemoglobin concentration (MCHC), differential leukocyte count, total serum protein were determined using several laboratory techniques. These changes of these parameters were presented in tables in relation to the ages of these animals.

Population Characteristics of Feral Horses on Cumberland Island, Georgia and Their Management Implications

Control of feral borse populations (Equus caballus) on public lands is restricted to nonlethal methods. These methods can limit population growth, however, efficacy may very among populations with differing demography and social structures Characteristics of many western feral horse populations are well documented, but fewer data are available for Atlantic barrier island populations. Therefore, we monitored a population of feral horses on Cumberland Island, Georgia from 1986 to 1990, Population growth averaged 4.3% annually with a stable age structure. Mean size of bands with ≥ 1 stallion was 4.6 horses. The adult sex ratio for the population was 0.6 females: 1.0 males. About 66% of mares foaled during a given year and no juvenile females foaled. Annual survival rates averaged 61.1% for female foals. 58.8% for male foals, and 92.4% for mares. Most bands contained a dominant or codominant stallion, mares and-or juvenile females, and foals Most mares (62.5%) changed bands ≥ 1 time during our study. Bachelors represented 50.4% of stallions. These population characteristics differed from other feral horse populations. The small band size, large number of bachelors, high degree of band instability, and codominance of band stallions on Cumberland Island likely will linut the efficacy of some forms of nonlethal population control.

Evaluation of the catabolic activity of cartilage by measurement of serum keratan sulfate concentration in foals

Abstract Objectives To determine keratan sulfate (KS) concentration in the serum of foals at the early stage of growing, and to evaluate the role of serum KS as a cartilage catabolic marker, comparing its values with the fluctuation of serum alkaline phosphatase (ALP) activity as a measurement of osteoblastic activity. Animals 12 foals with normal growth and 3 foals with joint abnormalities within 18 months after birth. Procedure Measurement of KS concentration and ALP activity in serum and radiographic and physical examinations were done. Results In all foals, serum KS concentration was high from 1 week after birth to 3 months of age, while serum ALP decreased with aging. The value started to decrease rapidly from 3 to 5 months of age, then gradually reached adult values. During the first 3 months, KS concentration in male foals was significantly higher than that in female foals. In 3 foals which had joint problems, KS concentration was higher than that in normally growing foals at 1 week, and at 1, 2, and 3 months of age. Conclusions Cartilage catabolic activity is higher in developing foals up to 3 months of age, suggesting that the immature joint at this time could be easily affected by any factor of loading. Moreover, though only 3 diseased foals were examined, higher serum KS concentration in these foals suggest that this variable might be a useful measure of joint diseases, even at an early stage of life in foals. (Am J Vet Res 1997;58:925–929)

Epidemiological investigation of equid herpesvirus-4 (EHV-4) excretion assessed by nasal swabs taken from thoroughbred foals

Equid herpesvirus-4 (EHV-4) was detected in nasal swabs taken from foals using a PCR based test and this information used to study the epidemiology of EHV-4 disease on three Australian Thoroughbred stud farms in NSW in 1992. There was a very high level of agreement (kappa value of 0.84) between the PCR results and virus isolation using cell culture techniques. There was a strong seasonal distribution of EHV-4 shedding. Twenty-five of 26 positive samples were collected in January and March with the remaining positive sample collected in February. Foals with clinical signs of upper respiratory tract infection per se were no more likely to be shedders of EHV-4 (odds ratio [OR] 1.4, 95% confidence limits [CL] 0.5–3.8). However, EHV-4 was more likely to be isolated from foals exhibiting copious serous or mucopurulent nasal discharge than those with no clinical signs (OR 4.6, 95% CL 1.1–19.0 and OR 2.5, 95% CL 0.8–8.0, respectively). The month of the year was more important than weaning or age as a risk factor for excretion of EHV-4. Male foals and those with a history of respiratory disease that had required veterinary treatment were more likely to shed EHV-4.

Determination of the early age of onset of equine recurrent laryngeal neuropathy. 1. Muscle pathology.

The age of onset of equine recurrent laryngeal neuropathy has not been ascertained, although the clinical condition of left laryngeal hemiplegia ("roaring") has been recognized for centuries. The purpose of this study was to evaluate the laryngeal muscles of draft horse foals for the presence of fiber-type grouping, indicating denervation and reinnervation, and to determine if histological evidence of recurrent laryngeal neuropathy was present. Abductor and adductor laryngeal muscles from the left and right sides were collected immediately after euthanasia from male draft horse foals, six less than 2 weeks and four 6 months of age, and stained for myosin ATPase. A morphometric test was used to objectively evaluate several areas from each muscle for fiber-type grouping. Extensive fiber-type grouping which was characteristic of recurrent laryngeal neuropathy was found in one of the young foals and all of the older foals. Four of the young foals had some areas of fiber-type grouping suggestive of mild, early changes associated with recurrent laryngeal neuropathy. One of the young foals had no fiber-type grouping present in any of the laryngeal muscles evaluated. These findings suggest an early age of onset of recurrent laryngeal neuropathy.

A case of male infanticide in Equus przewalskii

Following the introduction of a new stallion to a band of E. przewalskii mares two births, both of male foals, resulted in foal death due to injuries sustained in the first day of life. Neither foal was sired by the new herd stallion. The second foal death was the results of an observed attack on the newborn male and is described here. Subsequently births in the same enclosure and, in one instance, to the same mare whose previous foal was killed, were of foals sired by the new stallion and were uneventful, with 3 male foals surviving to date.

Ultrasonography in a Przewalski's horse mare, [formula omitted][formula omitted

Somali wild ass (Equus africanus somaliensis) are the most endangered species of wild equid, and little is known about their reproductive biology. Here, we describe social interactions and glucocorticoid production of five pairs of Somali wild ass females and their foals, which were born within a two-month period at the Saint Louis Zoo. Behavioral data were recorded from 0 to 3 months (Infant), and again from 6 to 12 months of age (Older Foal). Fecal samples were collected three times a week for 12 months, starting when foals were born, and analyzed for glucocorticoids using a validated assay. Generalized linear mixed models assessed differences in behavior and glucocorticoid concentrations between foals and mothers, in regard to foal sex, foal age, and season. Nursing bout frequency and total nursing duration, but not bout duration, decreased with age. Low nursing rates were still observed in 11 to 12-month-old foals, suggesting that weaning occurs after one year. Rates of social behaviors were similar between mothers and their foals, and rates of agonistic behavior were similar to rates of affiliative behavior. Male foals initiated and received agonistic behaviors more than female foals. Patterns of interactions varied with foal age. Infants interacted primarily with their mothers, whereas interactions among foals were common during the Older Foal period. Glucocorticoid concentrations of foals and mothers varied in relation to foal age; concentrations for both were highest in the first months of life. Seasonal differences in glucocorticoid concentrations were also observed, but no evidence of elevated glucocorticoid production was found except around the time of parturition. This suggests that neither mothers nor foals experienced chronic stress. Our study presents new information on the biology of Somali wild asses and it is one of the few to document behavior and physiology in a non-domestic equid. This information may contribute to improved management of ex situ populations by enhancing individual welfare and increasing reproductive success.

Male mule foal qualifies as the offspring of a female mule and jack donkey

Whereas mules are normally considered sterile, reports of fertile female mules persist. However, none subjected to cytogenetical and blood typing analyses could be confirmed as having indeed been mules that transmitted maternal markers to their alleged offspring. Reported here is the case of a cytogenetically verified female mule whose alleged male foal qualifies as offspring by a male donkey. The male foal is karyotypically a mule.

On lactation and associated behaviour in a natural herd of horses

Developmental changes in time spent suckling and related mother-foal behaviour are described in an unmanaged herd of Camargue horses. Male foals spent about 40% more time suckling than females during the first 8 weeks. Body weight did not differ between the sexes but time-budgets did: males grazed less and were more active. If pregnant, the typical multiparous mare nursed her foals for 35–40 weeks, males and females alike, and weaned them 15 weeks before the next foaling. Primiparae lactated longer and weaned closer to the next foaling by 5 weeks. The mares played an active role in regulating the time spent suckling in early, and particularly in late lactation.