**2. Evaluation of the ovaries during AI**

Ultrasonic evaluation of the ovaries should be considered a routine part of the reproductive ex‐ amination particularly in cattle. A 5MHz transducer has greater resolution and is more suita‐ ble for evaluation of the ovaries than a 3 or 3.5MHz transducer. Follicles, like other fluid structures, are non echogenic, and therefore, appear on the ultrasound image as black, circum‐ scribed structures which are spherical to irregular in shape (Fig 1). The irregular shapes are at‐ tributable to compression by adjacent follicles and luteal structures of the ovarian stroma.

ter AI. The accuracy of detecting foetal viability may approach 100% [Lamb, 2001]. A techni‐ cian with a trained eye has the capability of accurately assessing the age of the foetus based on foetal size [Curran, 1986]. At 60 to 85 days of pregnancy the trained user can even deter‐ mine foetal sex by the absence and/or presence of the foetal genitalia with over 95% accura‐ cy. These two features alone provide many options for the use of ultrasound in reproductive management practices [Palmer and Drinacourt, 1980; Muller and Wittkowski, 1986; Kastelic et al, 1989; Romano and Masgee, 2001]. Development of integrated reproductive manage‐ ment systems that combines ultrasound with new and existing reproductive technologies will further enhance the practical applications of ultrasonography. In summary, current and future applications of ultrasonography hold tremendous potential to enhance reproductive

The incorporation of ultrasound in reproductive research has also led to greater understand‐ ing of ovarian physiology. Ultrasound has been used extensively in the development of con‐ trolled breeding programs involving both oestrus and ovulation synchronization for effective timed AI. Sequential monitoring of dynamic changes in a follicular population dur‐ ing the oestrous cycle has been made possible by ultrasonography [Driancort et al, 1991; Garcia et al, 1999; Ginther 1993]. This capability has helped unlock some of the mysteries of folliculogenesis. During anoestrous, inactive ovaries are readily differentiated from func‐

Further, when choosing bulls, many producers are faced with difficult decisions regarding the contributions of both maternal and carcass traits. Not only do the attributes of multiple breeds vary, but variation within breed is also substantial. By combining ultrasound and AI, a producer can develop a breeding program that optimizes both maternal and carcass traits [Travene et al, 1985; Kahn, 1992]. Using ultrasound, producers may determine females that are pregnant with AI-sired heifer calves based on the age and sex of the foetus [Travene et al, 1985; Kahn, 1992]. In a typical commercial cow-calf production environment controlled breeding seasons range from 60 to 120 days. By using ultrasound as early as 30 days after the end of the breeding season in seasonally breeding animals, producers can divide their herd into cows that became pregnant early or late in the breeding season, and open cows which can subsequently be managed appropriately in accordance with their reproductive

Ultrasonic evaluation of the ovaries should be considered a routine part of the reproductive ex‐ amination particularly in cattle. A 5MHz transducer has greater resolution and is more suita‐ ble for evaluation of the ovaries than a 3 or 3.5MHz transducer. Follicles, like other fluid structures, are non echogenic, and therefore, appear on the ultrasound image as black, circum‐ scribed structures which are spherical to irregular in shape (Fig 1). The irregular shapes are at‐ tributable to compression by adjacent follicles and luteal structures of the ovarian stroma.

management and improve reproductive efficiency in bovine.

142 Success in Artificial Insemination - Quality of Semen and Diagnostics Employed

tional ovaries with ultrasonography.

status to run the production at reasonable cost.

**2. Evaluation of the ovaries during AI**

**Figure 1.** Several medium sized follicles observed in mare. Ultrasonogram taken with 5MHz curvilinear array scanner (Hitachi 405, Germany). Source: Lemma et al, 2006

Follicles as small as 2 - 3 mm can be seen and the corpus luteum can usually be identified throughout its functional life [Lemma et al, 2006] Estimating the stage of oestrous cycle, as‐ sessing the status and number of preovulatory follicles, determining ovulation, monitoring the development and morphology of corpus luteum are among the potential applications of ultrasonographic examination of the ovaries [Fortune et al, 1988; Garcia et al, 1999; Noble et al, 2000; Evans et al, 2000; Evans, 2003]. The number and sizes of follicles on a given ovary will vary widely and are dependent on the time of year and the reproductive stage in differ‐ ent animals [Vandeplassche et al, 1981; Perry, 1991; Godoi et al, 2002]. Many small follicles are observed during early dieostrus and these follicles will grow larger at mid-cycle. The dominant or ovulatory follicle will develop at a rate of 1.5 to 2.5mm per day in cattle [Drian‐ court et al, 1988] few days before ovulation which are all easily monitored ultrasonically to determine the date of ovulation and hence subsequently fix the appropriate time for insemi‐ nation. During oestrous cycles in cattle dominant follicles reach a maximum diameter of ap‐ proximately 10 - 20 mm and the largest subordinate follicles reach maximum diameter of approximately 8 mm. Cows ovulate at about 12 hours after the end of the oestrus period. The time for insemination may therefore range between 6 and 24 hours prior to ovulation [Arthur, 2001; Ball and Peters, 2004]

The appearance of dominant follicles is often accompanied by an outward manifestation of behavioural oestrus. However, cows with dominant follicle that is about to ovulate do not always show overt oestrus and this is becoming one of the greatest hindrance to the success of AI. Whilst good oestrus detection does not necessarily guarantee good reproductive per‐ formance, poor oestrus detection makes poor performance hard to avoid [Arthur, 2001]. Poor oestrus manifestation and failure to detect oestrus further hinders insemination at the correct time which is an important cause of fertilization failure. Insemination very early in oestrus also causes reduced fertility; possibly due to reduced sperm survival rates before fertilization [Andrew *et al.,* 2004].

manifestation, respectively. The mean size of the follicles for the same time group of animals was 13.5±3.2mm, 13.0±4.7mm and 11.1±5.8mm, respectively. Only 39.4% were found to be fit for insemination (showing most oestrus signs, follicular diameter ≥12mm and/or were brought for AI ≤12hrs of oestrus manifestation) during the ultrasonic evaluation. However, all animals were inseminated giving a pregnancy rate of only 30.0% compared to 61.5% for the fit animals alone. It was concluded that the low conception rate, delayed time of insemi‐ nation, and the difference in the size of larger follicle indicate the incompatibility of visual heat detection and optimal time of insemination. This study clearly shows two important facts: cows showing oestrus do not necessarily carry mature follicles ready for ovulation, and ultrasonic evaluation of the ovaries right before AI can significantly improve pregnancy

The Role of Trans-Rectal Ultrasonography in Artificial Insemination Program

http://dx.doi.org/10.5772/52721

145

Furthermore, ultrasound has also great contribution to reproductive management through es‐ trus synchronization. By early detection of pregnancy post AI in synchronization the pitfalls of different factors involved in reducing reproductive performance could be identified and ac‐ cordingly mitigated. In a study [Hamid et al, 2012] conducted to evaluate the effects of artifi‐ cial estrus induction and breed, both were known to have significant effect on pregnancy rate (Table 2). Pregnancy was determined at day 26 post AI using a B-mode real time ultrasound with a 5MHz linear array transducer (Mindray, Hong Kong). The negative effect of poor nutri‐ tional management appropriate for cross breed animals, and the positive influence of estrus in‐ duction on first service pregnancy rate were identified. This information was useful in the

**Oestrus induced**

**Pregnancy rate [%]**

**p-value**

**cows**

**p-value No of cows at first AI**

rate by avoiding insemination of animals that are not fit for service.

decision making process on those animals that failed to be pregnant.

**Pregnancy rate**

Zebu 75 18 (24%) 62 30 (48.4%)

Cross 10 6 (60%) 0.018 15 7 (46.7%) 0.905 Total 85 24 (28.2%) 77 37 (48.1%) 0.009

**Table 2.** Comparison of first service pregnancy rate between oestrus induced and non induced cows (effect of heat

Reproductive ultrasonography has increased the knowledge of the changes during early pregnancy in different animals. With the use of a real-time, B-mode ultrasonography and 5 MHz transducer, pregnancy can be detected as early as 9 to 12 days post AI into gestation [Pierson and Ginther, 1984; Curran et al., 1986; Boyd et al., 1988]. A thorough understanding of the ultrasonic anatomy and dynamic changes in the uterus is essential for accurate preg‐

**[%]**

induction); and between breeds (zebu and Holstein cross cows)

**3. Application of ultrasonography in early PD**

**Breed Non oestrus**

**AI**

**induced cows**

**No of cows at first**

Many developing countries commonly relay on small holder dairy production system where owners cannot afford to keep a breeding bull and have to depend on AI services. The use of AI as the main method of breeding to improve performance means that the responsi‐ bility for oestrus detection falls upon the dairy owners who manage the herd [Lemma and Kebede, 2011]. In a study conducted to compare reproductive performance between farms using AI and natural service, the NSC, CCI and DALC were significantly higher (p<0.05) for farms using AI (2.1; 187.0 days and 185.7 days, respectively), compared to farms using natu‐ ral service (1.7; 159.1 days and 154.9 days), respectively [Lemma and Kebede, 2011]. In a dif‐ ferent study [Hansar et al, 2011] conducted to evaluate the efficiency of oestrus detection by small holder dairy owners in the success of AI and identify the role of ultrasonic evaluation of ovarian follicles before AI in improving pregnancy rate showed that ultrasonography can solve many problems of oestrus detection. In the same study, visual oestrus detection by dairy owners was assessed for validity using ultrasonic evaluation of the ovaries before AI with the following results (Table 1).


**Table 1.** Dairy cows and heifers that showed different types of oestrus signs prior to AI (n=60)

A significant difference (p<0.05) was observed in the mean diameter of largest follicle between the pregnant and non pregnant animals. Similarly, the duration from detection of estrus to AI was also significantly different (P<0.05) between successful and failed pregnancies. While none of the animals were waited until they exhibited standing estrus, the average duration to AI for animals that later became pregnant and showed both Vaginal discharge and mounting was 6.4hrs with 13.8mm average diameter of largest follicle. In contrast to this, those non preg‐ nant animals showing both mounting and Vaginal discharge were brought to AI on average af‐ ter 14.1hrs, and the average diameter of largest follicle was 9.7mm.

The mean (±SD) diameter of the largest follicle for animals showing both signs was 12.7±4.4 mm. Considering these estrus signs to be the best indicators of estrus as perceived by the dairy owners, 9, 5 and 6 animals were brought within 6 hrs, 7-14hrs and after 14hrs of heat manifestation, respectively. The mean size of the follicles for the same time group of animals was 13.5±3.2mm, 13.0±4.7mm and 11.1±5.8mm, respectively. Only 39.4% were found to be fit for insemination (showing most oestrus signs, follicular diameter ≥12mm and/or were brought for AI ≤12hrs of oestrus manifestation) during the ultrasonic evaluation. However, all animals were inseminated giving a pregnancy rate of only 30.0% compared to 61.5% for the fit animals alone. It was concluded that the low conception rate, delayed time of insemi‐ nation, and the difference in the size of larger follicle indicate the incompatibility of visual heat detection and optimal time of insemination. This study clearly shows two important facts: cows showing oestrus do not necessarily carry mature follicles ready for ovulation, and ultrasonic evaluation of the ovaries right before AI can significantly improve pregnancy rate by avoiding insemination of animals that are not fit for service.

oestrus also causes reduced fertility; possibly due to reduced sperm survival rates before

Many developing countries commonly relay on small holder dairy production system where owners cannot afford to keep a breeding bull and have to depend on AI services. The use of AI as the main method of breeding to improve performance means that the responsi‐ bility for oestrus detection falls upon the dairy owners who manage the herd [Lemma and Kebede, 2011]. In a study conducted to compare reproductive performance between farms using AI and natural service, the NSC, CCI and DALC were significantly higher (p<0.05) for farms using AI (2.1; 187.0 days and 185.7 days, respectively), compared to farms using natu‐ ral service (1.7; 159.1 days and 154.9 days), respectively [Lemma and Kebede, 2011]. In a dif‐ ferent study [Hansar et al, 2011] conducted to evaluate the efficiency of oestrus detection by small holder dairy owners in the success of AI and identify the role of ultrasonic evaluation of ovarian follicles before AI in improving pregnancy rate showed that ultrasonography can solve many problems of oestrus detection. In the same study, visual oestrus detection by dairy owners was assessed for validity using ultrasonic evaluation of the ovaries before AI

**(n=18)**

**Non-Pregnant After AI (n=42)**

fertilization [Andrew *et al.,* 2004].

144 Success in Artificial Insemination - Quality of Semen and Diagnostics Employed

with the following results (Table 1).

**Oestrus signs Overall (n=60) Pregnant After AI**

**Table 1.** Dairy cows and heifers that showed different types of oestrus signs prior to AI (n=60)

ter 14.1hrs, and the average diameter of largest follicle was 9.7mm.

Bellowing [%] 60.0 61.1 59.5 Mounting others [%] 66.7 77.8 64.2 Vaginal discharge [%] 83.3 88.9 83.3 Mounting and vaginal discharge 60.6 87.5 52.0 Diameter of dominant follicle [mm] 12.9±3.4 14.7±3.3 12.1±3.37 Estrus to AI [hrs] 13.3±9.3 10.5±6.9 15.10

A significant difference (p<0.05) was observed in the mean diameter of largest follicle between the pregnant and non pregnant animals. Similarly, the duration from detection of estrus to AI was also significantly different (P<0.05) between successful and failed pregnancies. While none of the animals were waited until they exhibited standing estrus, the average duration to AI for animals that later became pregnant and showed both Vaginal discharge and mounting was 6.4hrs with 13.8mm average diameter of largest follicle. In contrast to this, those non preg‐ nant animals showing both mounting and Vaginal discharge were brought to AI on average af‐

The mean (±SD) diameter of the largest follicle for animals showing both signs was 12.7±4.4 mm. Considering these estrus signs to be the best indicators of estrus as perceived by the dairy owners, 9, 5 and 6 animals were brought within 6 hrs, 7-14hrs and after 14hrs of heat

Furthermore, ultrasound has also great contribution to reproductive management through es‐ trus synchronization. By early detection of pregnancy post AI in synchronization the pitfalls of different factors involved in reducing reproductive performance could be identified and ac‐ cordingly mitigated. In a study [Hamid et al, 2012] conducted to evaluate the effects of artifi‐ cial estrus induction and breed, both were known to have significant effect on pregnancy rate (Table 2). Pregnancy was determined at day 26 post AI using a B-mode real time ultrasound with a 5MHz linear array transducer (Mindray, Hong Kong). The negative effect of poor nutri‐ tional management appropriate for cross breed animals, and the positive influence of estrus in‐ duction on first service pregnancy rate were identified. This information was useful in the decision making process on those animals that failed to be pregnant.


**Table 2.** Comparison of first service pregnancy rate between oestrus induced and non induced cows (effect of heat induction); and between breeds (zebu and Holstein cross cows)
