5. Reproductive traits in twin- and single-calving cows after calving

In Table 2, reproductive characteristics after calving are also presented with respect to the time from the calving to the service period [38]. The average number of days in the resting period on the farm was 75.8. The number of the calves had a strong effect on the length of the studied period (p = 0.043). The cows that had single calves took 73.6 days compared to the cows that had calved twins 78.0 days to recover.

The service period was analyzed in a separate study of the same herd data [40] and the average service period length was 44.6 for the herd overall (Figure 1). The single-calving cows had a shorter (44.4 days) service period than twin-calving cows (51.2 days), but this difference was not considered statistically significant (p = 0.111). It was found that roughly a third of the cows were put in calf by the very first insemination. Fifty percent of the cows that had single and twin calves were put in calf by the 40th and 48th day of service period, respectively. However, it was found that this 8-day difference was not a statistically proven difference (p = 0.653)

Figure 1. Cumulative proportion of cows that became pregnant on the course of insemination period [40].

between the groups of cows. This shows us that cows with single calvings and twin calvings respond in a similar way to rebreeding.

This study also showed that triplet-calving cows have even worse reproductive issues than twins, showing that the calving interval was 416 days in single-calving cows, 430 days in twincalving cows, and an excessive 487 days in cows that had triplets. The rest period after calving was shown to be 87 days for single-calving cows, 96 days for twin-calving cows, and 104 days for cows that had triplets. Similar delays were found in the service period, which was found to be 45 days in single-calving cows, 52 days in twin-calving cows, and 93 days in cows that had triplets. The percentage of successful first inseminations was found to be 49.11 for single-

Twin Calving and Its Connection to Other Economically Important Traits in Dairy Cattle

http://dx.doi.org/10.5772/intechopen.72905

69

The effect of twin calving on open days in Holsteins was studied in the USA [41]. The effects of twin calving in Holsteins were studied from a compilation of calving records from the Eastern Artificial Insemination Cooperative. Cows were grouped according to whether the twin calving was associated with dystocia. Records of each cow that had a twin calving were paired with records of a single-calving control herdmate. In the twin group of 175 cows associated with dystocia, after twin pregnancy, open days following twin calving were increased. In the twinning group of 367 cows with no dystocia at twinning, open days after twinning were increased by roughly 22 days, indicating a negative economic effect of twin calving suggesting increased rates of twinning via artificial selection or artificial induction of twinning in dairy

calving cows, 45.76 for twin-calving cows, and 28.57 for cows that had triplets.

6. Production traits in twin- and single-calving cows after calving

A study of the same dairy farm in northern Hungary [40] compared the total lactation performance data of 10,666 cows, in detail, examining the most economically important traits such as milk yield (kg), fat yield (kg), and protein yield (kg) and taking into account factors such as whether the cow had a single or twin calving, the proportion of Holstein Friesian genetics, the season the calving occurred in, the number of lactations, and the year of calving. The average total milk yield produced was 7140 kg, a noticeable difference was seen in comparison of single-calving and twin-calving cows in favor of single-calving cows (p = 0.013). On average, single-calving cows were found to produce 7390 kg of milk, whereas the twin-calving cows were found to produce 6890 kg. In terms of the type of calving, it was shown that cows that had twins yield on average 500 kg less milk than single-calving cows. As mentioned above, not only was total lactation yield (kg) evaluated but also fat yield (kg) and protein yield (kg) were evaluated. Regarding the fat yield, a meaningful distinction was recognized between single-calving cows and twin-calving cows (p = 0.030); single-calving

The overall standard lactation milk yield is 6685 kg. When the milk yield (p = 0.002), the fat yield (p = 0.001), and the protein yield (p = 0.004) were examined, they were found to have significant differences based on the type of calving. Twin-calving cows produced on average

However, contradicting results were found in another study [30]. Examining a herd of 23,588 cows of a local breed improved with Holstein Friesian between the years 2000 and 2008, it was

cattle would not be desirable.

cows gave 17 kg more fat.

410 kg less milk than single-calving cows.

On examination of the number of open days after calving [38], a relationship was found to twinning (Table 2). The average number of open days was 116.1. Based on the number of the calves, it was significantly different (p < 0.001). For the single-calving cows, there were 109.3 open days on average, whereas for the twin-calving cows, it took 123.1 days. In case of the twin-calving cows, the open days were 7 days more than the farm average.

Analyzing gestation length after calving [38], it was found that the average was 278.9 days. There was no significant difference between twin-calving and single-calving cows.

The length of the calving interval after calving was on average 403.9 days. However, there was significant deviation from the average in the twin- and non–twin-calving cows (p < 0.001). The calving interval following a twin calving was 6 days longer than the calving interval of singlecalving cows, and 13 days longer than the farm average. This is thought to be because after the twin calving the involution of the uterus takes longer, increasing the time between two calvings [6].

Another study [14] analyzed the reasons for culling in a herd of 23,588 cows of a local breed, 17 of which were improved with Holstein Friesian between the years 2000 and 2008. After having single calves vs. having twins or triplets, the culling patterns reveal some of the reproductive issues associated with multiple pregnancies. After single pregnancies, udder diseases account for 11.83% of culling, and fertility and reproductive diseases account for 34.58% of culling, whereas these figures are higher in multiple pregnancies with udder diseases accounting for 13.54% of culling and fertility and reproductive diseases accounting for 37.99% of culling (Table 3).


Table 3. Culling patterns in cows after single and multiple pregnancies (χ<sup>2</sup> = 28.26) [14].

This study also showed that triplet-calving cows have even worse reproductive issues than twins, showing that the calving interval was 416 days in single-calving cows, 430 days in twincalving cows, and an excessive 487 days in cows that had triplets. The rest period after calving was shown to be 87 days for single-calving cows, 96 days for twin-calving cows, and 104 days for cows that had triplets. Similar delays were found in the service period, which was found to be 45 days in single-calving cows, 52 days in twin-calving cows, and 93 days in cows that had triplets. The percentage of successful first inseminations was found to be 49.11 for singlecalving cows, 45.76 for twin-calving cows, and 28.57 for cows that had triplets.

between the groups of cows. This shows us that cows with single calvings and twin calvings

On examination of the number of open days after calving [38], a relationship was found to twinning (Table 2). The average number of open days was 116.1. Based on the number of the calves, it was significantly different (p < 0.001). For the single-calving cows, there were 109.3 open days on average, whereas for the twin-calving cows, it took 123.1 days. In case of the

Analyzing gestation length after calving [38], it was found that the average was 278.9 days.

The length of the calving interval after calving was on average 403.9 days. However, there was significant deviation from the average in the twin- and non–twin-calving cows (p < 0.001). The calving interval following a twin calving was 6 days longer than the calving interval of singlecalving cows, and 13 days longer than the farm average. This is thought to be because after the twin calving the involution of the uterus takes longer, increasing the time between two calvings [6]. Another study [14] analyzed the reasons for culling in a herd of 23,588 cows of a local breed, 17 of which were improved with Holstein Friesian between the years 2000 and 2008. After having single calves vs. having twins or triplets, the culling patterns reveal some of the reproductive issues associated with multiple pregnancies. After single pregnancies, udder diseases account for 11.83% of culling, and fertility and reproductive diseases account for 34.58% of culling, whereas these figures are higher in multiple pregnancies with udder diseases accounting for 13.54% of culling and fertility and reproductive diseases accounting for 37.99% of culling (Table 3).

Reasons for culling Proportion of production cycles interrupted due to

Production cycles interrupted due to selling or culling (n, %) 20,548 (27.74%) 458 (40.71%)

Sold for further breeding 13.81 9.61 Low yield 3.82 2.62 Udder diseases 11.83 13.54 Fertility and reproductive diseases 34.58 37.99 Infectious diseases (leukemia) 2.79 1.97 Old age 1.09 1.31 Metabolic and digestive diseases 2.06 3.93 Respiratory diseases 0.12 0.00 Diseases of the locomotor system 3.22 4.37 Accidents 21.27 17.25 Other 5.14 7.42

Table 3. Culling patterns in cows after single and multiple pregnancies (χ<sup>2</sup> = 28.26) [14].

selling or curling depending on type of pregnancy

Single pregnancy (%) Multiple pregnancy (%)

twin-calving cows, the open days were 7 days more than the farm average.

There was no significant difference between twin-calving and single-calving cows.

respond in a similar way to rebreeding.

68 Ruminants - The Husbandry, Economic and Health Aspects

The effect of twin calving on open days in Holsteins was studied in the USA [41]. The effects of twin calving in Holsteins were studied from a compilation of calving records from the Eastern Artificial Insemination Cooperative. Cows were grouped according to whether the twin calving was associated with dystocia. Records of each cow that had a twin calving were paired with records of a single-calving control herdmate. In the twin group of 175 cows associated with dystocia, after twin pregnancy, open days following twin calving were increased. In the twinning group of 367 cows with no dystocia at twinning, open days after twinning were increased by roughly 22 days, indicating a negative economic effect of twin calving suggesting increased rates of twinning via artificial selection or artificial induction of twinning in dairy cattle would not be desirable.
