Recibido: 23/09/2025 Aceptado: 08/01/2026 Publicado: 29/01/2026 UNIVERSIDAD DEL ZULIA Serbiluz Sistema de Servicios Bibliotecarios y de Información Biblioteca Digital Repositorio Académico 1 of 7 UNIVERSIDAD DEL ZULIA Serbiluz Sistema de Servicios Bibliotecarios y de Información Biblioteca Digital Repositorio Académico Assessment of growth rate in Purebred Arabian and Barbe Foals Evaluación de la tasa de crecimiento en potros de raza Pura Sangre Árabe y Barbo Bousmaha Fatma 1 , Berrani Abdelakader 1 , Ben Amor Saﬁa 2,3 , Meliani Samia 2,3* ¹ Nature and life sciences Facuty, University Ibn-Khaldoun of Tiaret, Tiaret 14000, Algeria. ² Higher School of Saharan Agriculture – El oued, 39000 Algeria. ³ SALAMA LAB, Higher School of Saharan Agriculture – El Oued, PB 90 Chouhada, El Oued 39011, Algeria *Corresponding author: melianisamia@hotmail.com ABSTRACT The main objecve of this study was to assess the inﬂuence of sex, breed, month of birth, and year of birth on the birth weight and postnatal growth performance of foals raised under standardized condions at the Chaouchaoua Naonal Stud of Tiaret, Algeria. A total of 97 foals (69 Arab and 28 Barb) were included in the study. Only live-born foals that survived beyond six months of age were considered. All animals were reared under the same housing, feeding, and management condions throughout the study. Data were retrospecvely collected from the oﬃcial birth records of the Naonal Stud Farm for the years 2017 to 2021. The following variables were analysed birth weight (in kg), body weight at ﬁrst and second weighing, average daily gain between birth and body weight at ﬁrst weighing, and between body weight at ﬁrst and second weighing. Weaning dates and weighing dates were also recorded. On average, the two weighing were carried out at approximately six-month intervals, allowing for the esmaon of growth rates over disnct phases. Analysis of the data by foal breed revealed a highly signiﬁcant diﬀerence (P < 0.005) in birth weight between the two groups. Arab foals had a signiﬁcantly higher mean birth weight (50.76 ± 5.08 kg) compared to Barb foals (46.82 ± 5.66 kg). This study provides valuable insights into the postnatal growth paerns of foals born at the Chaouchaoua Naonal Stud. These ﬁndings conﬁrm that breed signiﬁcantly inﬂuences birth weight and growth rate, with Barb foals outperforming Arab foals in average daily gains. Key words: Foal growth; birth weight; arabian horse; barb horse; av- erage daily gain. RESUMEN El objevo principal de este estudio fue evaluar la inﬂuencia del sexo, la raza, el mes de nacimiento y el año de nacimiento sobre el peso al nacer y el rendimiento de crecimiento posnatal de potros criados en condiciones estandarizadas en el Haras Nacional Chaouchaoua de Tiaret, Argelia. En total se incluyeron 97 potros (69 Árabes y 28 Barbos) en el estudio. Solo se consideraron los potros nacidos vivos que sobrevivieron más allá de los seis meses de edad. Todos los animales fueron criados bajo las mismas condiciones de alojamiento, alimentación y manejo durante el estudio. Los datos se recopilaron retrospecvamente a parr de los registros oﬁciales de nacimientos del Haras Nacional correspondientes a los años 2017 a 2021. Se analizaron las siguientes variables : peso al nacer (kg), peso corporal en la primera y segunda pesada, ganancia media diaria entre el nacimiento y peso corporal en la primera pesada, y entre peso corporal entre la primera y segunda pesada. También se registraron las fechas de destete y de pesada. En promedio, las dos pesadas se realizaron con un intervalo de aproximadamente seis meses, lo que permió esmar las tasas de crecimiento en fases disntas. El análisis de los datos según la raza de los potros reveló una diferencia altamente signiﬁcava (P < 0,005) en el peso al nacer entre los dos grupos. Los potros Árabes presentaron un peso medio al nacer signiﬁcavamente mayor (50,76 ± 5,08 kg) en comparación con los potros Barbos (46,82 ± 5,66 kg). Este estudio aporta información valiosa sobre los patrones de crecimiento posnatal de potros nacidos en el Haras Nacional Chaouchaoua. Nuestros hallazgos conﬁrman que la raza inﬂuye signiﬁcavamente en el peso al nacer y en la tasa de crecimiento, con los potros Barbos superando a los potros Árabes en las ganancias medias diarias. Palabras clave: Crecimiento del potro; peso al nacer; caballo árabe; caballo barbo; ganancia diaria media. https://doi.org/10.52973/rcfcv-e361803 Revista Científica, FCV-LUZ / Vol. XXXVI

Revista Cienﬁca, FCV-LUZ / Vol. XXXVI UNIVERSIDAD DEL ZULIA Serbiluz Sistema de Servicios Bibliotecarios y de Información Biblioteca Digital Repositorio Académico INTRODUCTION Equine breeding (Equus caballus) remains a major component of both economic acvity and cultural heritage in many regions worldwide, parcularly in North Africa, where horse populaons remain relavely high because of long- standing equestrian tradions. In parallel, equine producon systems are closely linked to equestrian sports and horse racing, alongside a sustained interest in the preservaon and promoon of tradional disciplines such as Fantasia [1]. Seasonal reproducve ming in horses ensures that foals are born under environmental condions that favour survival, with spring births generally oﬀering advantages over oﬀ-season births because of reduced thermoregulatory demands and lower immune stress [2]. Early foal growth is widely recognised as a key indicator of health status, vitality, and future developmental potenal. At birth, foal weight represents approximately 8–12 % of the dam’s body weight. In Thoroughbred populaons, mean birth weight (BW) typically centres around 55 kg, reﬂecng breed-speciﬁc neonatal growth potenal and highlighng the importance of BW as an indicator of early development and overall ﬁtness [3 ,4]. Foal body weight usually doubles during the ﬁrst month of life, and by the me of weaning, at six to seven months of age, it reaches nearly ﬁve mes its BW. This corresponds to approximately 220–260 kg in saddle horses and 300–400 kg in draﬅ breeds, represenng about 45 % of adult body weight [4]. By one year of age, this proporon increases to roughly 65 %, and by two years, foals generally aain 75–80 % of their mature body weight [5]. Growth and development in foals are inﬂuenced by a wide range of factors, including weaning age, housing condions, nutrional management, and climac condions. The ming of weaning is parcularly crical, as it can markedly aﬀect postnatal growth performance [6 , 7]. In addion, sex-related diﬀerences have been reported, with ﬁllies weighing on average 1.2 kg less than colts at birth across mulple regions, including Kentucky, the United Kingdom, and Australia, indicang a consistent eﬀect of sex on foal BW across populaons [8]. Furthermore, the season of birth plays a signiﬁcant role in determining both inial body weight and subsequent growth trajectory. Foals born in spring oﬅen exhibit higher growth rates, likely due to more favourable ambient temperatures and improved pasture availability during early development. Maternal parity also inﬂuences BW, as primiparous mares tend to produce lighter foals [7 , 8]. Several studies have shown that intrinsic factors, such as breed and dam age, together with extrinsic factors including season of birth and management pracces, signiﬁcantly aﬀect early growth parameters in foals [9]. Foetal size has been reported to decrease when the ﬁnal phase of gestaon coincides with winter months, with neonatal growth during the ﬁrst three months being correspondingly lower in foals born early in the year compared with those born later in the season [10], 11]. Moreover, maternal parity aﬀects placental development as well as postnatal growth and metabolism, with foals born to primiparous mares remaining smaller for several months aﬅer birth [12]. The primary objecve of the present study was to evaluate the inﬂuence of sex, breed, month of birth, and year of birth- on-birth weight and postnatal growth performance in foals raised under standardised management condions at the Chaouchaoua Naonal Stud in Tiaret, Algeria. MATERIALS AND METHODS The present study was conducted at the Chaouchaoua Naonal Stud, located in Tiaret Province, Algeria. This stud farm is dedicated to the conservaon and genec improvement of nave Algerian horse breeds, including the Arabian, Barb, Arab- Barb, and more recently, the Anglo-Arabian. The facility includes well-equipped infrastructure for equine breeding, such as stables, a farriery, a Veterinary inﬁrmary, a breeding courtyard, storage buildings for forage and equipment, and fourteen fenced pastures for seasonal grazing. Data were retrospecvely collected from the oﬃcial birth records of the Naonal Stud Farm for the years 2017 to 2021. However, data from 2019 were not available due to restricted access to the stud during the COVID-19 pandemic, as sanitary measures prevented all entry during that period. A total of 97 foals (69 Arab and 28 Barb) were included in the study. Only live-born foals that survived beyond six months of age were considered. All animals were reared under the same housing, feeding, and management condions throughout the study. The mares monitored in this study were between 3 and 15 years of age. However, neither maternal age nor maternal parity was considered in the analysis of their inﬂuence on foal BW or postnatal growth. The data were compiled in Microsoﬅ Excel® spreadsheets and included the following variables: foal identy (name, sex, breed, and date of birth), BW in kg, body weight at ﬁrst (W1) and second (W2) weighing, average daily gain between birth and W1 (ADG1), and between W1 and W2 (ADG2). Weaning dates and weighing dates were also recorded. On average, the two weighings were carried out at approximately six-month intervals, allowing for the esmaon of growth rates over disnct phases. For foals older than six months, body weight was measured using a barymetric tape. The animal was restrained, and the tape was placed just behind the withers, posioned vercally across the girth line. The weight was read directly from the scale marked on the tape. Before weaning, foals remained with their dams unl six months of age, beneﬁng from maternal lactaon. Weaning was carried out progressively: the mare and foal were ﬁrst isolated together in a 10 m² stall, then the mare was removed, leaving the foal alone to adapt. When weather condions allowed, all animals, including lactang mares, had access to grazing paddocks for a few hours daily. Stallions, however, remained in individual boxes to prevent accidental breeding and to preserve breed integrity. The feeding regime was based primarily on barley and hay. Barley was soaked in water prior to distribuon (48 hours (h) in winter, 24 h in summer) to improve digesbility. Feed was 2 of 7

Growth Rate in Purebred Arabian and Barbe / Bousmaha et al. UNIVERSIDAD DEL ZULIA Serbiluz Sistema de Servicios Bibliotecarios y de Información Biblioteca Digital Repositorio Académico distributed twice daily, with hay provided at 9:00 a.m. and barley at 2:00 p.m. Forage and water were available ad libitum. Lactang mares received 6 kg of hay and 5 kg of barley per day (d); pregnant mares were given 5 kg of hay and 4 kg of barley; stallions received 5 kg of hay and 4 kg of barley, with oats occasionally added during the breeding season. Weaned foals inially received 500 g of barley per day, progressively increased to 3 kg by the age of one year. Hay was distributed in group raons, approximately one bale per seven foals. Between the ages of one and two years, foals were fed 5 kg of hay and 3 kg of barley per d. Pelleted feed was provided as needed, depending on the animals’ physiological requirements and the stud’s budget. Straw was used as bedding based on availability and need. Health management included regular deworming and vaccinaon. Foals received anparasic treatment with Milbemycin and were vaccinated against tetanus between 4 and 6 months of age. Aﬅer weaning, treatments were administered every three months. Vaccinaon against rabies and equine inﬂuenza began at six months of age, followed by a booster one month later, then annual revaccinaon. Stascal analysis This was conducted using IBM SPSS® Stascs version 25. A one-way analysis of variance (ANOVA) was used to assess the eﬀect of four ﬁxed factors, sex (male or female), breed (Arab or Barb), month of birth (January to June), and year of birth (2017, 2018, 2020, 2021) on the growth parameters, an LSD test was performed to compare the diﬀerences between categories if a signiﬁcant diﬀerence is observed. Stascal signiﬁcance was set at P < 0.05. When signiﬁcant diﬀerences were detected, groups were disnguished using superscript leers in the tables. Non-signiﬁcant results were interpreted as P > 0.05. RESULTS AND DISCUSSION The data obtained is reported in TABLE I for the variaon between the two breeds studied. Analysis of the data by foal breed revealed a highly signiﬁcant diﬀerence (P < 0.005) in BW between the two groups. Arab foals had a signiﬁcantly higher mean BW (50.76 ± 5.08 kg) compared to Barb foals (46.82 ± 5.66 kg). However, no signiﬁcant diﬀerences (P > 0.05) were observed between the breeds in body weight at W1 and W2, nor in average daily gains (ADG1 and ADG2), although Barb foals exhibited slightly higher mean values in ADG1 (0.69 ± 0.28 kg/d) and ADG2 (0.95 ± 0.40 kg/d) compared to Arab foals (0.56 ± 0.37 kg/d and 0.79 ± 0.53 kg/d, respecvely). Comparisons based on sex (TABLE II) showed no signiﬁcant diﬀerences (P > 0.05) for any of the studied variables. Male and female foals exhibited comparable BW (50.51 ± 5.48 kg vs. 48.64 ± 5.47 kg), as well as similar values for body weights at W1 and W2, and for both ADG1 and ADG2. TABLE I Mean ± SD values of Birth Weigth, Average Daily Gain of foals variaon according to foal breed Breed BW (Kg) W1 (Kg) W2 (Kg) ADG 1 (Kg/d) ADG 2 (Kg/d) ARABE (n = 69) 50.76 ± 5.08** 187.22 ± 37.51 214.12 ± 44.22 0.56 ± 0.37 0.79 ± 0.53 BARBE (n = 28) 46.82 ± 5.66 180.04 ± 29.56 208.34 ± 33.08 0.69 ± 0.28 0.95 ± 0.40 Total (n=97) 49.62 ± 5.53 185.20 ± 35.45 212.45 ± 41.23 0.60 ± 0.35 0.84 ± 0.50 ** Indicates a signiﬁcant diﬀerence (P < 0.005) within the same column. (BW: Birth weight; W1: Body weight at ﬁrst weighing; W2 Body weight at second weighing; ADG1 Average daily gain between birth and W1; ADG2: Average daily gain between W1 and W2) TABLE II Mean ± SD values of Birth Weigth, Average Daily Gain of foals variaon according to foal sex BREED SEXE BW (Kg) W1 (Kg) W2 (Kg) ADG 1 (Kg/d) ADG 2 (Kg/d) Arabe Male (n = 38) 51.85 ± 4.89 192.53 ± 35.78 218.11 ± 41.34 0.56 ± 0.31 0.79 ± 0.46 Female (n = 31) 49.42 ± 5.07 180.71 ± 39.13 209.23 ± 47.75 0.57 ± 0.43 0.80 ± 0.61 Barbe Male (n = 13) 46.59 ± 5.39 181.67 ± 32.73 211.62 ± 31.29 0.71 ± 0.32 0.97 ± 0.43 Female (n = 15) 47.03 ± 6.07 178.73 ± 27.86 205.50 ± 35.40 0.67 ± 0.26 0.93 ± 0.39 Total (n = 97) 49.62 ± 5.53 185.20 ± 35.45 212.45 ± 41.23 0.60 ± 0.35 0.84 ± 0.50 (BW: Birth weight; W1: Body weight at ﬁrst weighing; W2 Body weight at second eighing; ADG1 Average daily gain between birth and W1; ADG2: Average daily gain between W1 and W2) The month of birth did not signiﬁcantly inﬂuence (P > 0.05) the growth performance or BW of the foals, although some numerical variaons were noted. Foals born in May recorded the highest mean BW (57.13 ± 9.54 kg), while those born in January showed the highest mean body weight at W2 (228.40 ± 43.27 kg). However, due to limited sample sizes in some months (notably may and june), these diﬀerences should be interpreted with cauon as shown in TABLE III. In this work, many signiﬁcant diﬀerences (P < 0.05) were observed between years for all variables (BW, W1, W2, ADG1, and ADG2), as indicated in TABLE IV. The foals born in 2020 had the highest BW (52.38 ± 5.66 kg) and ﬁnal weights (270.75 ± 25.21 kg), but surprisingly exhibited the lowest daily weight gains (ADG1: 0.29 ± 0.03 kg/d; ADG2: 0.37 ± 0.03 kg/d). In contrast, foals born in 2018 showed signiﬁcantly higher ADG1 (0.93 ± 0.40 kg/d) and ADG2 (1.33 ± 0.56 kg/d) despite having lower W1 and W2 values. The lowest mean BW was recorded in 2021 (44.85 ± 4.83 kg), which also corresponded to signiﬁcantly lower W1 and ADG2 values. 3 of 7

Revista Cienﬁca, FCV-LUZ / Vol. XXXVI UNIVERSIDAD DEL ZULIA Serbiluz Sistema de Servicios Bibliotecarios y de Información Biblioteca Digital Repositorio Académico TABLE III Mean ± SD values of Birth Weigth, Average Daily Gain of foals variaon according to Month of birth Month of birth BW (Kg) W1 (Kg) W2 (Kg) ADG 1 (Kg/d) ADG 2 (Kg/d) January (n = 21) 47.56 ± 5.26 192.83 ± 39.71 228.40 ± 43.27 0.58 ± 0.32 0.80 ± 0.46 February (n = 26) 49.08 ± 5.66 181.40 ± 31.51 207.65 ± 38.85 0.52 ± 0.23 0.72 ± 0.32 March (n = 33) 49.92 ± 4.84 184.45 ± 35.40 208.23 ± 40.11 0.68 ± 0.38 0.95 ± 0.56 April (n = 13) 51.22 ± 5.20 181.69 ± 42.66 210.42 ± 47.97 0.54 ± 0.49 0.76 ± 0.64 May and June (n = 4) 55.46 ± 2.37 196.50 ± 20.51 208.84 ± 21.45 0.90 ± 0.40 1.23 ± 0.52 Total (n = 97) 49.62 ± 5.53 185.20 ± 35.45 212.45 ± 41.23 0.60 ± 0.35 0.84 ± 0.50 (BW: Birth weight; W1: Body weight at ﬁrst weighing; W2 Body weight at second weighing; ADG1 Average daily gain between birth and W1; ADG2: Average daily gain between W1 and W2) The results of this study reveal a signiﬁcant eﬀect of breed on BW, with Arab foals (50.76 ± 5.08 kg) being signiﬁcantly heavier at birth than Barb foals (46.82 ± 5.66 kg) (P < 0.005). This observaon conﬁrms the inﬂuence of genec background on neonatal mass, in line with recent ﬁndings showing that breedrelated genec factors, along with sex and dam age, inﬂuence BW and other morphometric traits at birth in Arabian foals in Turkey [13], underlining breed-dependent diﬀerences in body mass accumulaon. The higher BW observed in Arab foals may be related to their larger mature size and higher skeletal mass compared to Barbs. This is consistent with recent ﬁndings showing that paerns of growth plate closure and skeletal maturity vary among horses, with overall development completed by approximately 2 years of age but with measurable variaon in ming and rates among individuals and breeds, supporng the concept that smaller, earlymaturing breeds may diﬀer from larger, slowermaturing types in growth dynamics [14]. Therefore, while Barb foals are oﬅen considered more precocious in development due to their smaller adult frame, the Arab breed demonstrates a stronger growth potenal from birth, consistent with their more substanal morphological proﬁle. TABLE IV Mean ± SD values of Birth Weigth, Average Daily Gain of foals variaon according to year of birth Year of Birth BW (Kg) W1 (Kg) W2 (Kg) ADG 1 (Kg/d) ADG 2 (Kg/d) 2017 (n = 24) 51.55 ± 3.62 ab 192.17 ± 16.49 a 211.42 ± 19.60 a 0.68 ± 0.16 a 0.93 ± 0.21 a 2018 (n = 29) 49.04 ± 5.05 b 162.64 ± 11.52 b 182.64 ± 18.47 b 0.93 ± 0.40 b 1.33 ± 0.56 b 2020 (n = 24) 52.38 ± 5.66 ac 232.42 ± 22.82 c 270.75 ± 25.21 c 0.29 ± 0.03 c 0.37 ± 0.03 c 2021 (n = 20) 44.85 ± 4.83 d 151.75 ± 18.19 d 186.95 ± 22.73 b 0.41 ± 0.07 c 0.58 ± 0.09 d Total (n = 97) 49.62 ± 5.53 185.20 ± 35.45 212.45 ± 41.23 0.60 ± 0.35 0.84 ± 0.50 a,b,c,d Indicates a signiﬁcant diﬀerence (P < 0.05) within the same column. (BW: Birth weight; W1: Body weight at ﬁrst weighing; W2 Body weight at second weighing; ADG1 Average daily gain between birth and W1; ADG2: Average daily gain between W1 and W2) Interesngly, despite the higher BW, Arab foals showed lower average daily gains (ADG) during both growth phases compared to Barbs. Speciﬁcally, ADG1 (from birth to ﬁrst weighing) was 0.56 ± 0.37 kg/d for Arabs versus 0.69 ± 0.28 kg/d for Barbs, and ADG2 (between the ﬁrst and second weighing) was 0.79 ± 0.53 kg/d for Arabs versus 0.95 ± 0.40 kg/d for Barbs. Although these diﬀerences were not marked as stascally signiﬁcant in the current dataset (P > 0.05), the tendency suggests that Barb foals, despite their lighter BW, exhibited a faster postnatal growth rate compared to their Arab counterparts. This paern may be partly explained by growth eﬃciency rather than growth capacity alone. The Barb horse, adapted to arid and rugged environments, may exhibit more eﬃcient resource ulizaon and postnatal growth compensaon, especially during the early months. Furthermore, the Kentucky Equine Research Staﬀ [15] report emphasized that ponies and smaller breeds tend to reach a higher proporon of their adult weight and size at a younger age than larger breeds, which connue growing over a longer period. These ﬁndings support the idea that Barb foals, represenng a smaller-framed nave breed, might undergo more accelerated growth in early stages, while Arab foals, as a more mesomorphic and larger-frame breed, sustain a steadier but longer growth curve. Regarding body weight at W1 and W2, Arab foals maintained slightly higher absolute weights at both checkpoints (W1 = 187.22 kg; W2 = 214.12 kg) compared to Barb foals (W1 = 180.04 kg; W2 = 208.34 kg), although the diﬀerences were not stascally signiﬁcant (P > 0.05). This conﬁrms that while Arab foals start heavier and remain heavier overall, Barb foals tend to narrow the weight gap progressively through faster growth, as reﬂected in their higher ADG values. These results highlight a dual growth paern between the two breeds: Arab foals display a higher inial mass and consistent linear growth, while Barb foals compensate for lower BW through enhanced postnatal growth dynamics. This breed-speciﬁc growth behaviour has important implicaons for nutrional strategies, management ming, and genec selecon programs in equine breeding systems. The analysis of growth performance according to sex showed no stascally signiﬁcant diﬀerences (P > 0.05) between male and female foals for any of the measured parameters, including BW, body weight at W1 and W2, and average daily gains (ADG1 and ADG2). These ﬁndings are consistent with those of Dias de Castro et al. [6], who reported that the inﬂuence of sex on 4 of 7

Growth Rate in Purebred Arabian and Barbe / Bousmaha et al. UNIVERSIDAD DEL ZULIA Serbiluz Sistema de Servicios Bibliotecarios y de Información Biblioteca Digital Repositorio Académico growth is minimal before puberty and becomes more apparent aﬅer 12–18 months of age, when male foals tend to surpass females in weight gain and skeletal development. In this study, although male foals exhibited a slightly higher mean BW (50.51 ± 5.48 kg) than females (48.64 ± 5.47 kg), the diﬀerence was not stascally signiﬁcant. In a longitudinal study of Thoroughbred foals, body weight and linear measures (e.g., wither height) did not diﬀer signiﬁcantly between males and females through the ﬁrst year of life when managed under uniform condions [6]. These results also corroborate previous ﬁndings indicang that male foals tend to be heavier at birth than females. For instance, Pagan et al. [7] reported average birth weights of 56.5 kg for colts versus 55.3 kg for ﬁllies across Thoroughbred populaons in Kentucky, the United Kingdom, and Australia. Similarly, data from Turkish Thoroughbred populaons suggest slightly higher average weights for male foals, consistent with the general trend of sex-related diﬀerences in neonatal mass [14]. However, in contrast, a high signiﬁcant diﬀerence in body size between sexes, suggesng that such diﬀerences may depend on breed, age range, and environmental condions was described [16]. Although the ADG were nearly idencal between sexes in this study (around 0.60 kg/d during the ﬁrst period and 0.83– 0.84 kg/d during the second), females showed a slightly faster growth rate during the later phase. This subtle diﬀerence likely reﬂects the earlier skeletal and muscular maturaon observed in ﬁllies compared to colts. Recent research has shown that horses generally reach skeletal maturity by about two years of age, but females tend to mature earlier, with faster closure of growth plates and diﬀerent bone-turnover paerns [17], 18 , 19]. As a result, ﬁllies oﬅen achieve adult size and proporons sooner than males, which may explain their transient advantage in growth velocity during the second phase. Taken together, these ﬁndings support the hypothesis that sexual dimorphism in equine growth is minimal before puberty and that growth rate and ﬁnal size diverge gradually thereaﬅer, under the inﬂuence of sex hormones and metabolic changes. From a management standpoint, these results underline the importance of monitoring both sexes under similar condions during the ﬁrst two years, as the diﬀerences in growth remain limited and should not necessitate diﬀerenated rearing pracces during this period. The analysis of foal growth according to the month of birth showed moderate variability in both BW and postnatal weight gains, although these diﬀerences were not stascally signiﬁcant (P > 0.05). Nevertheless, some trends can be idenﬁed that align with known physiological and environmental inﬂuences related to seasonality and forage availability. Foals born in May and June, although represented by very small sample sizes (n = 3 and n = 1, respecvely), displayed the highest BW (57.13 ± 9.54 kg and 53.78 kg) and the most elevated ADG, especially in June (ADG1 = 1.18 kg/d, ADG2 = 1.59 kg/d). These values should be interpreted with cauon due to limited stascal power, yet they may reﬂect the nutrional beneﬁts associated with late gestaon occurring during periods of lush spring pasture [20]. Favourable climac condions and the abundance of nutrient-rich forage in spring can enhance maternal nutrion, improving fetal growth and promong beer neonatal vitality. Conversely, foals born earlier in the year, notably in January and February, exhibited lower BW (47.56 ± 5.26 kg and 49.08 ± 5.66 kg, respecvely) and relavely slower ADG, parcularly in February (ADG1 = 0.52 ± 0.23 kg/d, ADG2 = 0.72 ± 0.32 kg/d). These results may be explained by seasonal limitaons in forage quality during the winter months, when mares are typically fed hay and concentrates, which are oﬅen lower in digesble nutrients and protein compared to fresh pasture. This seasonal nutrional constraint has been emphasised by Robles et al. [21] who reviewed how reduced availability and quality of forage, parcularly during winter in late-gestaon mares, may compromise the nutrional support required for opmal fetal development. Interesngly, foals born in March and April showed intermediate BW (49.92 ± 4.84 kg and 51.22 ± 5.20 kg, respecvely) and moderate to high growth rates (ADG1 from 0.54 to 0.68 kg/d), suggesng that mid-gestaon during winter followed by early lactaon in spring provides relavely balanced condions for both maternal and neonatal nutrion. This supports the concept that seasonal transions, such as from late winter to early spring, provide a nutrional window that promotes more stable growth trajectories in foals. These ﬁndings are also consistent with Veronesi et al. [22], who showed that maternal hormonal proﬁles change from prefoaling to late pregnancy in response to environmental and nutrional condions. Such hormonal adjustments may inﬂuence gestaon length and fetal development, potenally resulng in earlier parturion or subopmal growth under adverse seasonal or nutrional circumstances, although no stascally signiﬁcant diﬀerences were observed in this study (P > 0.05), the trends across birth months reinforce the idea that seasonal variaons in climate and feed availability inﬂuence maternal nutrion, which in turn aﬀects BW and early postnatal growth. Therefore, opmal reproducve scheduling and nutrional management of broodmares according to forage cycles could contribute to more uniform and improved growth performance in foals. The analysis of foal growth according to the year of birth revealed signiﬁcant interannual variaons (P < 0.05) in all measured parameters: BW, body weight at W1 and W2, and ADG during both growth periods. These diﬀerences can be largely aributed to environmental condions, parcularly climac variability and its impact on nutrional availability. Foals born in 2020 had the highest average weights (52.38 ± 5.66 kg at birth, 232.42 ± 22.82 kg at W1, and 270.75 ± 25.21 kg at W2), yet paradoxically exhibited the lowest ADG (ADG1 = 0.29 ± 0.03 kg/d, ADG2 = 0.37 ± 0.03 kg/d). These results suggest that although the foals were born heavier and remained heavier over me, their postnatal growth rate was markedly slower, possibly due to management or nutrional constraints during this speciﬁc year. In contrast, the 2018 cohort displayed signiﬁcantly lower body weights (BW = 49.04 ± 5.05 kg; W1 = 162.64 ± 11.52 kg; W2 = 182.64 ± 18.47 kg), but had the highest growth velocies (ADG1 = 0.93 ± 0.40 kg/d; ADG2 = 1.33 ± 0.56 kg/d), suggesng compensatory growth potenally triggered by favorable nutrional recovery postnatally. This could reﬂect the interplay between early environmental adversity and enhanced nutrional support during lactaon or pre-weaning phases. 5 of 7

Revista Cienﬁca, FCV-LUZ / Vol. XXXVI UNIVERSIDAD DEL ZULIA Serbiluz Sistema de Servicios Bibliotecarios y de Información Biblioteca Digital Repositorio Académico The low BW observed in 2021 foals (44.85 ± 4.83 kg) aligns with signiﬁcantly lower body weights at W1 and W2 and modest ADG values, conﬁrming an overall subdued growth trajectory for that year. These paerns are consistent with the ﬁndings of Meliani et al. [3], who reported that periods characterized by reduced rainfall or elevated ambient temperatures are associated with shorter gestaon duraon in Arabian mares. Such environmental constraints were shown to adversely inﬂuence maternal nutrional status and placental nutrient transfer to the fetus, ulmately leading to lower BW. These ﬁndings are also consistent with Silva et al. [20], who demonstrated that environmental factors, parcularly thermal stress associated with high ambient temperatures and humidity, are negavely correlated with gestaon length in Thoroughbred mares. Hoer climac condions during late pregnancy were associated with shorter gestaon duraon, indicang that climate-related stress can inﬂuence reproducve ming and may indirectly aﬀect fetal development. In contrast, unfavorable weather paerns, such as those potenally observed in 2021, can reduce forage quality and delay or impair fetal development. Similarly, the Forage quality and nutrient composion vary markedly with season, harvest me and climac-soil condions, such that winter conserved forages oﬅen have lower digesbility and higher ﬁbre content compared with fresh spring growth [23]. The interannual variability in forage quality may thus explain some of the year-to-year diﬀerences in both BW and growth rates observed in this study. These results suggest that ﬂuctuaons in climac and nutrional condions across years can strongly inﬂuence fetal development and early postnatal growth. Similar ﬁndings were reported by Hacan et al. [12], who demonstrated that birth year had a signiﬁcant eﬀect on foal body measurements at birth, reﬂecng environmental and management variaons. Likewise, Silva et al. [24] emphasized that climac condions and annual diﬀerences in feeding resources are important determinants of gestaon length and early-life performance in mares. Collecvely, these observaons conﬁrm that the year of birth serves as a reliable proxy for environmental and nutrional contexts, reinforcing the importance of adapve feeding strategies and systemac pasture monitoring to ensure consistent growth performance in equine breeding systems, parcularly under increasing climate variability. CONCLUSION This study provides valuable insights into the postnatal growth paerns of foals born at the Chaouchaoua Naonal Stud, with parcular aenon to the eﬀects of breed, sex, birth month, and birth year. These ﬁndings conﬁrm that breed signiﬁcantly inﬂuences BW and growth rate, with Barb foals outperforming Arab foals in ADG. Sex showed no signiﬁcant eﬀect before puberty, although females demonstrated slightly faster growth—consistent with known precocity in ﬁllies. The inﬂuence of the birth year highlighted the impact of environmental and climac variability, with dry years altering growth trajectories. Month of birth also contributed to ﬂuctuaons in weight and growth, likely due to seasonal feed quality. These variaons emphasize the mulfactorial nature of equine growth and the importance of adapng management strategies. Opmizing nutrional intake and environmental condions could enhance developmental outcomes. 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