With a footprint of 21,081 square kilometers, Mizoram, an among India’s shortest states and fifth in size, is distinguished by its mostly hilly terrain with only a few flat areas. The climate of Mizoram ranges from moisture sub-tropical to moist tropical, with pleasant winters and moderately warm summers. The summertime temperatures fluctuate from 18°C to 29°C, while winter temperatures usually vary between 11°C and 24°C. From May to September, the state has regular monsoons that bring with them a lot of rain. Notably, Mizoram experiences little rainfall and a dry winter (Indian State Forest Report, 2011).         
       
Animal husbandry plays a vital role in Mizoram, offering economic stability to a significant portion of the vulnerable tribal population. It serves as a safety net in cases of crop failures due to natural disasters, as 85% of the rural population relies on agriculture as their primary livelihood (Economic Survey of Mizoram, 2022). Dairy farming is primarily conducted by medium-scale farmers of Mizoram (Talukdar et al., 2022). Because of the steep terrain, intensive rearing methods are preferred, which results in dairy cattle spending most of their lives in sheds. Seasonal fluctuations in feed availability have a substantial impact on these animals’ health and productivity (Boro et al., 2021). Mizoram relies on supplies from surrounding states because the majority of its components in concentrate feed products are not sourced locally. The animals are fed leaves from trees of bananas and other forest plants due to the longer periods of drought (November to June), which worsen the lack of food. The state’s poor-quality feed is a result of heavy rains and subsurface leaking. Fodder production is further limited by inadequate irrigation infrastructure, particularly during the dry season. The region’s dairy cattle output is subpar due to a combination of restriction housing, inadequate feeds as well fodders and environmental issues. Additionally, there is currently very little information available about the reproductive and productive potential of dairy cattle raised in the states. These factors led to the proposal of the current study, which aims to investigate the reproductive along with productive outcomes of HF cattle from standard breeds in Mizoram farm conditions.

The study was carried out at Central Agricultural University’s Livestock Farm Complex, College of Veterinary Sciences and Animal Husbandry, Selesih, Mizoram. 35 holstein friesian ´ local crossbred cattle raised in the Livestock Farm Complex’s cattle unit had their production and reproductive performance data gathered from farm records over a 14-year period (2010 to 2024). Standard housing and a balanced diet consisting of both dry and green forage were given to the animals. The milch animals received enough amounts of concentrates according to their needs for production and maintenance. The animals were immunized and dewormed according to their regular regimens. Lactation length, dry time, lactation production, daily mean average milk yield and peak milk yield/lactation were the productive parameters that were examined. Analysis was done on the reproductive factors, such as age during initial fertile service, age at maiden calving, gestation length, service period, calving interval and number of services per conception. The Economic Survey of Mizoram (2022) divided the data into four seasons: winter (November-January), spring (February-April), summer (May-August) and autumn (September-October) in order to examine the impact of season on crossbred cattle performance.
       
To produce significant findings and reasonable conclusions, the gathered data was combined, collated and put through a number of suitable statistical tests. According to Snedecor and Cochran (1995), statistical analysis was applied to the data.

The lactation lengths for the 1^st, 2^nd, 3^rd, 4^th and 5^th parities were 411.54±16.42, 420.55±21.43, 417.70±28.51, 412.12±21.52 and 405.75±63.35 days, respectively (Table 1). The overall lactation length for all the parities was 414.60±10.52 days. The length of lactation did not significantly differ between the parities, according to statistical analysis. Prasanna et al., (2023) reported a shorter lactation period than the current study. For crossbred dairy cattle, an intercalving time of 365 days (12 months), a lactation period of 305 days and a dry phase of 60 days are thought to be optimum. However, in Indian conditions, an intercalving duration of up to 15 months is also seen as desirable (Shastry and Thomas, 2021). Longer lactation may have been caused by the current study’s shorter dry time and higher service period.


       
The dry period of HF crossbred cattle reared under farm condition of Mizoram during 1^st, 2^nd, 3^rd, 4^th and 5^th parity were 63.17±0.75, 63.67±0.58, 69.43±3.85, 65.67±3.62 and 64.67±3.63 days, respectively with overall dry period for all parities was 65.49±1.13 days. Statistical analysis showed non-significant difference between the dry periods. Longer dry periods compared to present results were reported by Vijayakumar et al., (2019). A dairy cow’s dry period is an important indicator of both reproductive and productive efficiency. A pregnant cow’s fetal growth may be adversely affected by an excessively short dry phase, which may also have an impact on milk output during the next lactation. On the other hand, a cow’s poor effective as well reproductive efficiency is indicated by an overly protracted dry period (Borpujari et al., 2019). For dairy cows to remain healthy, happy and productive throughout the dry season, it is essential to maintain the proper balance. The study’s overall dry time of 65.49±1.13 days might be considered ideal.Top of Form
       
The lactation yield in HF crossbred cattle were observed for the first, second, third, fourth and fifth parity were 2825.23±162.24, 2995.39±212.56, 3042.73±268.47, 2668.06±109.51 and 2470.63±324.74 liters, respectively (Table 1). Overall lactation yield of all parity was 2866.27±100.55 liters. Statistical analysis shows non-significance in the lactation yield among the parties. From the data, it was observed that, lactation yield was in increasing trend from 1^st to 3^rd parity and thereafter it started to decline in 4^th and 5^th parity. The results obtained in the present study are comparable to reports of Prasanna et al., (2023). The milk yield not only directly impacts the economic productivity of the animal but also plays a significant role in determining the overall economic viability of dairy enterprises. Under Indian condition, lactation yield of crossbred cattle varies from 2453 to 5256 liters (Shastri and Thomas, 2021). The overall lactation milk yield of 2866.27±100.55 litres noted in the current study was within the acceptable range.
       
The average daily milk yields for HF crossbred in parity 1^st, 2^nd, 3^rd, 4^th and 5^th were 6.86±0.28, 7.24±0.42, 7.35±0.54, 6.55±0.32, 6.31±0.91 litres, respectively. Statistical analysis revealed non-significant differences among the different parities. The overall average daily milk yield for all the parities was 6.97±0.19 litres. Lower average daily milk yields compared to the present study was documented by Kabir and Islam (2009). Higher average daily milk yields than to present study was reported by Tomar et al., (2023). The average daily milk yield recorded in present study was found to be within the acceptable range as recorded in different parts of the country. Mizoram is a hilly state and there is prolong period of green fodder scarcity during dry months (December to June). Jungle tree leaves like jack fruit, peepal, bamboo including the banana leaves are the main roughage fed to the animals during the dry season. Fodder produced in the state are also poor is quality due to poor quality of soil. Considering the green fodder availability, average daily milk yield of 6.97±0.19 liters may be considered as acceptable (Talukdar et al., 2016a).
       
The peak milk yields (PMY) recorded in the present study for parity 1^st, 2^nd, 3^rd, 4^th and 5^th were 10.16±0.57, 12.01±0.76, 11.45±0.97,10.20±0.76 and 10.63±1.71 liters, respectively. The overall peak milk yield across the parities was found to be 10.87±0.37 liters. The similar findings of PMY with the present study were reported by Varaprasad et al., (2013). Prasanna et al., (2023) reported that the milk production varies as per feeding practices, milking system, health programs, breeding system and management of dairy animals. Peak milk yield of present study under farm condition of Mizoram was found to be optimum.
       
The average age at first fertile service in HF crossbred cattle was 711.88±42.55 days (Table 2). Age at first fertile service was found to be less than the present finding in HF×Hariana (Dhara, 1999). The higher values for age at the first fertile service than the present finding was reported by Singha et al., (1990). The variation of results reported by different workers with the present findings might be due to the differences in breed, plane of nutrition, housing, climate, hormonal profile etc. (Talukdar et al., 2013).
       
The average gestation length of HF crossbred cattle in the present study for 1^st, 2^nd, 3^rd, 4^th, 5^th parity and the overall were 280.44±0.86, 279.57±0.89, 279.57±0.89, 280.88±1.90, 285.20±4.25 and 280.65±0.61 days, respectively. Non-significant variations were found in statistical analysis between parities. Shorter gestation length compared to present results was observed by Mondal et al., (2005) for Jersey cross. Higher gestation length compared to presents results were reported by Rahman and Kalita (2015) in native cattle of Mizoram-Zobawng. The gestation length is not greatly altered in response to variations in feeding, housing etc. rather all these factors affect the sizes of developing foetuses. The overall gestation length of the present investigation was aligned within normal range.
       
The average age at first calving (AFC) in HF crossbred cattle was 1012±45.67 days (Table 2). As per Shastri and Thomas (2021) the age at first calving (AFC) for holstein friesian (HF) cows should fall within the range of 801 to 1080 days where as Rahman and Alemam (2008) observed to be 30 months. The overall AFC noted in the present investigation for HF crossbred cows was in accordance within the recommended range (Borpujari et al., 2018). The AFC is primarily influenced by factors such as nutrition from birth to calving, effective management practices such as insemination, monitoring for estrus signs, proper housing management etc.


       
The service period of HF crossbred cattle raised under farm condition of Mizoram for 1^st, 2^nd, 3^rd, 4^th and 5^th parity were 197.52±13.18, 207.08±16.78, 214.88±25.98, 240.40±11.48 and 210.85±20.91 days, respectively with overall service period for all parities was 206.88±08.81 (Table 2). Statistical analysis revealed non-significant difference between the service periods. Shorter service period was reported by Prasanna et al., (2023). Higher service period compared to present study was reported by Sreedhar et al., (2013). The Normal standard service period for cattle is established to be within the range of 60-90 days (Talukdar and Talukdar, 2017). However, in the present study service period has surpasses this normal range, which might be due to reproductive disorders, nutritional deficiencies, stall feeding housing system (Boro et al., 2022). The suboptimal nutritional content of the locally grown fodder might have also contributed anestrus in the animals which might have resulted in prolonged service period recorded in the present study (Boro et al., 2021).
       
The overall number of services per conception at farm condition of Mizoram was 3.68±0.18 (Table 2). The similar finding of present study was reported by Vijayakumar et al., (2019). Lower number of service per conception than present study was reported by Tomar et al., (2023).  Number of services per conception (NSPC) expresses the fertility level of the dairy herds (Talukdar et al., 2016b). The NSPC significantly impacted by lactation length, placenta expulsion time, herd and milk yield season (Rahman and Alemam, 2008). The higher number of services per conception (3.68±0.18) noted in the present study suggests poor reproductive efficiency of the HF crossbred cattle. Poor quality of fodder available in the research area combined with stress of stall-feeding practice might have affected the reproductive health of the cattle, leading to higher number of services per conception in the present study (Talukdar et al., 2015).
       
The present findings of calving intervals for the parity 1^st, 2^nd, 3^rd, 4^th, 5^th and overall are 477.57±16.69, 488.64±25.66, 495.14±33.65, 525.40±26.53, 490.09± 12.73 and 488.09 ± 11.73 days, respectively (Table 2). The lower calving interval to current findings was reported by Prasanna et al., (2023). The higher calving interval to current findings was reported by Rahman and Kalita (2015). The inter calving period is consisting of service period and gestation period. In the present study, service period was recorded as 206.88±08.81, which might have resulted in higher inter calving period. Inter calving period up to 15 months can be considered good under Indian condition (Shastry and Thomas, 2021). In the present study the average inter calving period was recorded as 488.09±11.73 days (around 16 months), which might be considered as acceptable one considering the limiting factors of dairy farming of the region like scarcity of feed and fodder, poor quality of fodder, common practice of stall feeding due to limited plain area etc. (Talukdar et al., 2016b).
       
The overall finding of average daily milk yield (lit) in HF crossbred cattle during winter, spring, summer and autumn seasons across the parities were 6.95±0.27, 6.43±0.24, 7.30±0.25 and 7.17±0.28, respectively (Table 3). Statistical analysis found non-significant differences in ADMY between the different seasons in all the parities. Ahmad et al., (2007) recorded comparatively greater milk yield in Jersey cows during winter followed by autumn, summer and   spring season. However, in contrast, Madke et al., (2011) observed higher milk yield during winter season as then the summer season. Wondifraw et al., (2013) observed decreased milk yield in deoni x HF crossbred cow’s calved during summer season. The results of the present study indicate uniformity in production performance across all seasons, with slightly increased in summer and autumn. This could be attributed to the improved availability of fodder during the summer compared to other seasons. From the data it was observed that, although non-significant, numerically higher milk yield was recorded during summer and autumn. Higher the accessibility of green fodder during season might have resulted in higher milk production in cows as compared winter and spring season. Although, fodder supply is less during winter and spring, cold suitable climate present might have favored high milk yield during winter and spring months. On the other hand, fodder supply is limited, moderately cold climate might have compensated the loss of milk production during winter and spring months.


       
The year-wise average daily milk yield (lit) in HF crossbred cattle from 2010 to 2023 were 5.4, 6.1, 7.4, 6.6, 6.9, 5.7, 5.8, 6.3, 6.5, 7.7, 8.3, 8.6, 7.8 and 7.9, respectively and month wise average daily milk yields were 6.6, 6.4, 6.6, 6.4, 6.3, 6.5, 7.2, 7.2, 7.2, 7.2, 7.1, 7.0, 7.2 and 6.8, respectively. The overall average daily milk yield from January to December (2010 to 2024) is 6.9 liters. The variations in milk yield during different years might be due the differences in management and prevalence of diseases (Talukdar et al., 2020).

In conclusion, the current study’s findings showed that the main problem with HF crossbred cows raised in Mizoram farms was their older age initially fertile service as well as longer service time. Although the milk production outcome of HF cross-bred cows raised on Mizoram farms was determined to be satisfactory, there is still potential for improvement. Season has little effect on the productivity of HF crossbred livestock raised in Mizoram farms.

The authors declare that there are no conflicts of interest regarding the publication of this article. No funding or sponsorship influenced the design of the study, data collection, analysis, decision to publish, or preparation of the manuscript.