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Relationship of Age at First Calving, First Lactation Milk Yield, Reproductive Performance and Diseases in Simmental Dairy Cows in Turkey


Relationship of Age at First Calving, First Lactation Milk Yield, Reproductive Performance and Diseases in Simmental Dairy Cows in Turkey

Nurcan Karslioglu Kara*

Department of Animal Science, Faculty of Agriculture, Bursa Uludag University, 16059, Bursa, Turkey


The aim of this research was to determine the relationship between age at first calving (AFC) and first lactation milk yield [adjusted 305-day (MY305)], reproductive performance [days open (DO), calving interval (CI)] and diseases (lameness, mastitis, metritis and dystocia) in Simmental dairy cows bred under Turkey conditions. A total of 1110 Simmental cows (first calving to second calving) were assessed according to study criteria. While the relation between AFC and disease incidence and MY305 was not found significant, the relation between AFC and CI and DO was found significant and the optimum interval of AFC was determined 684≤ İBY≤730 d for minimum CI and DO. Even though relation between AFC and diseases was not significant, it can be said that the same interval is advantageous for low disease incidence in Simmental cows. Furthermore, it can be accepted that the same interval is optimum also for the best lactation milk yield since it was not found a significant relationship among the average milk yields according to AFC. In conclusion, it can be said that planning the reproductive management practices according to these results will be beneficial for the optimal balance between economic benefit, animal health and milk yield.

Article Information

Received 14 July 2021

Revised 25 January 2022

Accepted 11 February 2022

Available online 15 March 2022

(early access)

Published 19 October 2022

Key words

Cow health, Reproduction, Milk yield, Dairy cow, Simmental


* Corresponding author:

0030-9923/2023/0001-77 $ 9.00/0

Copyright 2023 by the authors. Licensee Zoological Society of Pakistan.

This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (


Due to the rapid increase of intensive herd sizes in recent years, herd management strategies have become even more important for sustainable production. Animal health, reproductive condition and milk yield are considered important indicators for proper herd management (Okuyucu et al., 2018). On the other hand, some herd management practices, such as reducing the age at first calving aimed at reducing rearing costs may have a negative impact on animal health, reproductive performance and milk yield. Hence, it has been reported that calving at very early age may adversely affect milk performance and that heifers are more susceptible to certain health issues, especially dystocia, due to the fact that they are physically under-developed at the start of their first lactation (Hoffman and Funk, 1992). Although older age interval is being recommended for first calving for some breed and breeding systems, various research has shown that calving between 22-24 months in order to reduce breeding costs is suitable without any adverse effects on milk yield and animal health throughout the heifer’s productive life (Hoffman, 1997; Nilforooshan and Edriss, 2004). In accordance, provide of the optimal balance between economic benefit, animal health and milk yield is mandatory.

The aim of this study was to determine the relationship between age at first calving (AFC) and milk yield adjusted 305 days (MY305), reproductive performance and animal health in Simmental dairy herds in terms of providing the optimal balance between economic benefit, animal health and milk yield and increase the success of herd management practices accordingly.


Selection of herd

Study was carried out in one commercial dairy farm (3,000 Simmental cows) which is one of the biggest dairy farms located in west central Bursa, Turkey because of elimination of some environmental factors like as climate or nutrition and management practice that will be able to effect on results.

Selection of cows

Lactations with milk yields outside the range 2,000 to 12,000 L and DIM 260 to 400 days and cows that do not comply with the descriptive values of the calving age according to the calving order reported by Kumlu and Akman (1999) were excluded from the study. In accordance, a total of 1110 Simmental cows that born in 2016 completed their first lactation and gave their second calving were included in the study. The first calvings occurred between April 2018 and June 2019, and the second calvings February 2019 and August 2020. AFC (age at first calving, day), MY305 (milk yield adjusted 305 days, L), DO (days open), CI (calving interval, day) and health records (yes, no) were collected from the herd database.

Statistical analyses

For analyses, cows were divided into groups with mean ± 1 standard deviation width according to AFC and MY305 and the relation between these groups and disease incidence was investigated as used Chi-square tests. Also, ANOVA was used to investigate whether the difference between AFC groups in terms of CI, DO and MY305 or not and when necessary, Duncan’s multiple range test was used. Means of cows with each health problem and healthy cows were compared with the t-test to determine whether the health problems had an effect on AFC, CI, DO and MY305 or not. SPSS Inc (2008) was used for statistical analysis.


As descriptive statistics in this study, the average AFC, MY305, and CI was found 706.89 ± 1.41 days, 6928.50 ± 33.51 L, 377.87 ± 1.44 days, respectively in the study herd. Lameness has been determined to be the most common health problem observed 32.2% in the study herd. Mastitis, metritis and dystocia followed with of 29.3%, 14% and 8%, respectively. In terms of first lactation MY305, the result of this study was found higher than results reported by Cilek and Tekin (2005), Ozkan and Gunes (2011), Okuyucu et al. (2018) and lower than the result reported by Kucuk-Baykan and Ozcan (2017) while they have been observed to be coherent with results reported for various regions of Europe by Perišić et al. (2009). When the study results were evaluated for AFC, it is seen that AFC was earlier according to the national or international research’s results (Akbulut, 1998; Kocak et al., 2008; Szewczuk et al., 2015; Fedorovych, 2017). This result is decisive for herd economics and sustainability and can be explained that the animal group constituting the study materials having reached early two-thirds of mature weight which is considered a physical indicator of suitable time for insemination as reported by Mourits et al. (1997). Moreover, this result also exhibits the success and the importance of herd management programme for animal tracking practised in this herd before, during and after inseminations. When the effect of AFC on MY305 and reproductive performance investigated, the results are as shown in Table I. Contrary to studies reporting importance of positive correlation between AFC and MY305 (Krpálková et al., 2014) or studies reporting of negative correlation (Curran et al., 2013), in this study, it was not found significant difference exists between mean milk yields of animals in AFC groups. The difference of the results in studies on the effect of optimum first calving age on milk yield for different breeds so far establishes the importance of the effect of factors such as the breed being studied, environment, practised herd management programme etc. Under the circumstances, every result obtained shall constitute data in terms of performance information pertaining to the studied breed.

On the other hand, it has been determined that the difference observed as a result of the study in terms of DO and CI as reproductive performance criteria for animals in different AFC groups was found significant (P<0.05). Under the circumstances, the first thing to consider is whether there is any difference between AFC groups in terms of first service interval (FSI) after calving. Average FSI was found 67.28 ± 0.42 days in this study and this value is favourable for good reproductive management (Esslemont and Kossaibati, 2000; Uygur, 2004). When AFC groups were evaluated for FSI, the difference between


Table I. Effects of AFC on CI, DO and MY305 in Simmental dairy cows in Turkey.

AFC (d)





Mean ± SE

Mean ± SE

Mean ± SE

< 684


377.67 ± 2.46 †‡

95.83 ± 2.09 †

6905.81 ± 55.99

684 – 730


373.88 ± 2.10 †

93.92 ± 1.86 †

6904.19 ± 54.10

731 – 777


382.95 ± 4.08 †‡

100.35 ± 3.40 †‡

6977.30 ± 84.47

> 777


387.64 ± 4.65 ‡

108.02 ± 4.76 ‡

7059.67 ± 101.42



377.87 ± 1.44

96.82 ± 1.26

6928.89 ± 33.51


AFC, Age at first calving; CI, Calving interval; DO, Days open; MY305, Milk yield adjusted 305-day; †,‡ Means in a column with no common superscript differ; *, denote statistical significance at the P<0.05.


groups was not found significant (Table II). This result is indicated that there is a problem regarding the conception rate in the first AI in the herd with a mean DO of 96.82 ± 1.26 days or in another point of view, there is a problem regarding service per conception. Accordingly, DO and in parallel with DO, CI has prolonged. While many factors such as AI technician (age, skills, serving internal or external) the season of AI, the semen used, etc. can be effective on DO (Bhave et al., 2021); there are also lots of studies reporting the effect of AFC on in AI. Hence, Ettema and Santos (2004) reported that the lowest DO occurred in the youngest group with AFC <23 months; Banos et al. (2007) reported longer DO and CI for the young group with AFC within 18-23 months interval, with 7% higher service per conception and 7.5% higher rate of return. Similarly, Krpálková et al. (2014) and Eastham et al. (2018) reported higher DO and CI in young group with AFC <26 months. According to the results of this study, the AFC interval suitable for the lowest DO and CI is found to be 684≤ AFC ≤730 days (22.5≤ AFC ≤24 months) (P<0.05). As reported by other researchers, the result obtained is important for rapid genetic improvement, increase productive life and for the decrease in herd renewal costs (Ettema and Santos, 2004; Nilforooshan and Edriss, 2004).

Table II. Mean ± SE of FSI in different AFC groups.

AFC (d)



< 684


65.69 ± 0.64


684 – 730


68.67 ± 0.70

731 – 777


68.26 ± 1.15

> 777


66.89 ± 1.51



67.28 ± 0.42


AFC, Age at first calving; FSI, First service interval; NS, not significant.


When the relationship between AFC and diseases investigated, it was seen that disease incidence increases with increased AFC except for dystocia (Table III) but this relationship was not found significant. The reason for this result can be appropriate rearing, feeding and preventive veterinary practices in the postpartum period. Another possible reason can be the animal group constituting the study material was young. As a matter of fact, Dohoo et al. (1984) has reported a linear relationship between age and disease incidence. Still, it can be mentioned that the optimum AFC interval for minimum health problem is the optimum 684≤ AFC ≤730 days interval as determined for minimum DO and CI in this study. When the study material was assessed in terms of recorded health problems, the results as shown in Table IV. It was found that AFC is higher and MY305 is lower in cows with lameness (P<0.05). There are studies that reported a decrease in milk yield for cows with lameness (Amory et al., 2008; Charfeddine and Pérez-Cabal, 2017). As to high AFC in cows with lameness, study result is consistent with results as reported by Mason (2017). The researcher has reported that the incidence of lameness in cows calving at younger ages is lower than cows calving at later ages.

One reason for this can be that the changes in hoof structure and flexor tendons following the calving be causing fewer complications in younger animals as reported by Webster (2001). One other reason may be the body weight of the animals according to the age of first calving. Even though body weights were not evaluated in the study, Singh et al. (2012) reported that the percentage changes in body weight in animals were associated with the lameness incidence and that the incidence increased as the weight increased. Incidence of lameness is high in dairy cattle herds and arrangements are unfortunately limited for yield and in feeding program that supports the high milk yield that for decreasing this incidence. For this reason, it may be pointed out that for such type of herds; practises to strengthen and protect foot and leg health such as regular claw trimming, manure management, foot bath, proper bedding etc. are more of a necessity than choice. When compared the cows with dystocia and without, it was found that lower MY305 and AFC and higher DO and CI in cows with dystocia. However, the differences between groups were not found significant despite studies reporting otherwise. This result may be explained with dystocia score. Disease records that belong to cows were collected from herd records (yes, no) so, the dystocia score was evaluated as “unassisted” and “assisted” in the study performed by Johanson and Berger (2003). Although there is no common way of determining the level of calving difficulty, some other researchers suggested different scoring for more accurate assessment. Hansen et al. (2004) suggest a four-point scoring system of calving difficulty: (1) easy, (2) easy with assistance, (3) difficult but without veterinary assistance and (4) difficult with veterinary assistance. Ettema and Santos (2004) also distinguished four levels of calving difficulty but defined them differently: (0) no assistance with normal delivery of a live calf, (1) no assistance with normal delivery of a stillborn calf, (2) some assistance required for extraction of the calf and (3) difficult calving with forced extraction of the calf. Considering this information, the non-existence of difference between groups can be explained that dystocia records in the herd actually being non-assisted instances according to other evaluation systems.

Animals have completed involution periods after calving without any problems and their reproductive performance or milk yield being adversely non-affected. While the milk yield was found to be low for animals with mastitis which is in concordance with many preceding studies (P<0.01), was not found a significant relation between mastitis and reproductive parameters. This result can be explained that the effect of efficient herd health management where early diagnosis and proper treatment protocols are performed in time and correctly as reported by Fourichon et al. (2000). When compared the cows with metritis and without, it was found that decreasing in MY305 and AFC and increasing DO and CI in cows with metritis. While the difference was not found significant in between groups in terms of MY305 and AFC was found significant for DO and CI (P<0.01). This result in terms of the relation between metritis and DO and CI corresponded with the results of current studies (Vieira-Neto et al., 2016; Dubuc and Denis-Robichaud, 2017). Postpartum uterus infections such as metritis effects increasing CI directly since they prolong the FSI and DO (Foldi et al., 2006).

In this study, the DO and CI in the group with metritis was observed to have prolonged for 11 and 13 days, respectively. According to these results, in view of heat occurs every two to three weeks on average (Kojima, 2003), the 13 days of difference for CI can also be explained as one heat has been missed on average due to metritis. The negative effects of uterus diseases on fertility reported by current studies (Pinedo et al., 2020; Pérez-Báez et al., 2020) support these results.


Table III. Relation between AFC and disease incidence.

AFC (d)

















< 684













684 – 730

















731 – 777













> 777














AFC, Age at first calving; NO, Non observed; O, Observed; NS, not significant.


Table IV. Relation between diseases and milk yield and reproductive parameters.







Mean ± SE

Mean ± SE

Mean ± SE




6985.83 ± 40.58


704.40 ± 1.62


377.65 ± 1.85

95.76 ± 1.54



6808.78 ± 59.00

712.13 ± 2.72

378.35 ± 2.19

99.06 ± 2.20




6943.62 ± 34.67

707.59 ± 1.49

374.73 ± 3.63

94.90 ± 3.60



6767.85 ±127.00

699.22 ± 4.10

378.16 ± 1.54

97.00 ± 1.34




7026.73 ± 38.45


706.07 ± 1.62

378.59 ± 1.80

97.06 ± 1.51



6692.57 ± 65.15

708.86 ± 2.82

376.15 ± 2.29

96.25 ± 2.29




6942.05 ± 36.37

713.20 ± 4.41

376.14 ± 1.51


95.28 ± 1.33




6845.92 ± 85.70

705.88 ± 1.48

388.82 ± 4.40

106.53 ± 3.68


MY305, Milk yield adjusted 305-day; AFC, Age at first calving; CI, Calving interval; DO, Days Open; **,* denote statistical significance at the P<0.01, P<0.05 respectively; NO, Non observed; O, Observed.


Table V. Relation between MY305 and diseases.

MY305 (L)






























5254.1 – 6370.6













6370.7 – 7487.1













7487.2 – 8603.7













> 8603.7















MY305, Milk yield adjusted 305-day; **, denote statistical significance at the P<0.01; NO, Non observed; O, Observed.


Therefore, accurate assessment of factors in after calving such as birth stress, negative energy balance and rapid body condition loss which increase the risk of uterus infection and reduce the immune system in this period is critical. Accordingly, it can be said that follow-up of animals and taking protective cautions until the 3rd and 4th week after calving when bacterial contamination significantly decreases (Williams et al., 2007) are important and priority in increasing the reproductive performance within the herd. Finally, the relationship between MY305 and diseases was investigated and the relation between MY305 and mastitis was found important in animals of different milk yield groups (P<0.01), (Table V). According to this result, it can be said that mastitis incidence is low in high milk yield groups. It would be more accurate to interpret this result as a milk yield has been increased because of a decrease in mastitis incidence. Results of similar studies on this subject both national and international are in support of this interpretation (Kocak, 2006; Dhakal et al., 2016; Grayaa et al., 2019).


As a conclusion, it can be said that for Simmental breed cows bred in intensive herd, for the purposes of establishing the optimal balance between economic benefit, yield and animal health in the herd, the most suitable interval of AFC for maximum reproductive performance is 684≤ AFC≤730 days. Since was not found a significant difference between lactation milk yields according to AFC groups, it could be accepted the same interval as optimum for the best lactation milk yield and the mean lactation milk yield was 6904.19 ± 54.10 L in this interval. Although there was no significant difference between in AFC groups in terms of diseases observed, it can be seen that the optimum interval of AFC is the same for the lower incidence of lameness and mastitis that affect MY305 and metritis that affect fertility. Age at first calving is an important factor in the cost of rearing replacements in all dairy herds and the results of this study are important in terms of length of the rearing period and decreasing rearing cost as a management factor in Simmental dairy herds. Nevertheless, to achieve clearer conclusions regarding about performance of Simmental cows, do more studies that involved more animals and also considering the effects of different environmental factors would be beneficial.


Author would like to thank the dairy farm that was involved in this long-term study and all its employees.

Statement of conflict of interest

The authors have declared no conflict of interest.


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