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The present study investigates the susceptibility of two imported dairy cattle breeds to Algerian local climatic conditions, with a primary focus on heat stress (HS) and its repercussions on fertility traits. The dataset comprises 20,926 artificial insemination records involving 6,191 Prim'Holstein and 5,279 Montbéliarde cows. The animals originated from three distinct agro-ecological regions: littoral (L), semi-arid (SA), and arid (Ar), characterized by average annual Temperature-Humidity Index (THI) values of 75.2, 69.53, and 74.75, respectively. Logistic and linear regression models were performed to analyze the relationship between the THI on the AI day, season, and agro-ecological origin of the animals with the Conception Rate at 1st Artificial Insemination (CR 1stAI), Conception Risk (CR), Services per Conception (SPC), and reproductive period (RP). The results demonstrated a significant negative impact (P < 0.001) of THI > 72 compared to THI ≤ 72 on CR1st AI and CR for both cattle breeds (Prim'Holstein: -49.7% and - 17%, respectively; Montbéliarde: -20.7% and - 15%, respectively). Seasonal effects revealed a notably higher CR1stAI in winter and spring (≈ 25%) for Prim'Holstein and Montbéliarde cows compared to summer (19.41%) and autumn (19.12%), respectively. Furthermore, a reduced likelihood of conception at 1stAI and subsequent AI was observed during summer (0.839) and autumn (0.818) compared to winter for the Montbéliarde cows. Taking into account the littoral region as a reference, the likelihood of 1stAI success increased for both breeds in the SA region and decreased for the Ar region (P < 0.001). SPC increased for both breeds in THI > 72 categories (Prim'Holstein: 6.3%, Montbéliarde: 7.1%, P < 0.01), in the Ar region (Prim'Holstein: 30.9%, Montbéliarde: 26%, P < 0.001), and in the SA region (4%, P < 0.05) compared to the L region No significant seasonal effect on SPC was observed for either breed (P > 0.05). The RP increased in the THI > 72 category (Prim'Holstein: 4.1%, Montbéliarde: 7.4%, P < 0.001) and in the Ar region (Prim'Holstein: 122%, Montbéliarde: 73.4%) for both breeds. RP decreased in autumn compared to winter (Prim'Holstein: 15.3%, Montbéliarde: 8.4%). This study underscores the adverse impact of mild to severe heat stress (HS) and related factors (season, region) on fertility of Prim'Holstein and Montbéliarde cows under Algerian conditions, emphasizing the necessity for heat stress mitigation strategies, especially in adverse littoral humid and Saharan-arid environmental conditions., Competing Interests: Declarations. Competing interests: The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (© 2024. The Author(s) under exclusive licence to International Society of Biometeorology.)

This study assessed the effect of heat stress mitigations on the physiological, behavioural, and hormonal responses of buffalo during the hot summer season. Twenty Murrah buffalo male calves were distributed randomly into controlled (C, n = 10) and treatment groups (T, n = 10). The buffalo calves in the C group were housed in the existing shed (10-12-ft height and 10-ft width). Buffalo calves of the T group were allocated in the modified shed: 15-ft height and 20-ft width along with time-controlled pressure mist with fans and rubber mats on the floor. Fans were running all days. The cool water was misted on calves at the rate of 1 min in 5 min, from 11:00 to 18:00 h. The water misting system was installed below the roof, but at 3.5 m above the floor. The calves' body weight, rectal temperature, infrared temperature of the eye, blood samples, respiration rate, and pulse rate were recorded fortnightly for two consecutive months. In one-way ANOVA, rectal temperature, eye temperature, cortisol level, and afternoon's respiration and pulse rate were higher in the calves of C group than that of T group (P < 0.05). Conversely, eating and resting time (min/day) and triiodothyronine were lower in the calves of C group than that of T group (P < 0.05). Therefore, an increase in shed's height and width, using rubber mats on the floor, and cool water misting to buffaloes during the hot summer seasons positively influence their physiological, hormonal, and behavioural responses., (© 2022. The Author(s) under exclusive licence to International Society of Biometeorology.)