REFERENCE : Luttgenau et al. Ultrasonographic examination reduces the percentage of unsuccessful inseminations in dairy cows. Theriogenology, 2016, 85, 664-670.

BACKGROUND

• One in five cows is not actually in heat at insemination
• Manual identification of the presence of a follicle and/or its consistency is a risk factor for infertility

HOW DID THEY DO IT ?

Two groups of 300 dairy cows (2.8 lactations on average, of which 30% were primiparous; inseminated 73 to 74 days on average after calving; with an average body score of 3.3 and 3.4): the first group was palpated and the second palpated and ultrasounded.

Their criteria at palpation:

• Position of horns: totally or partially in the pelvic cavity
• Symmetry or not of the horns
• Consistency of the horns: flaccid, firm or tonic
• Presence of uterine content: little, medium or abundant
• Ovarian structures (follicle, corpus luteum or cyst): presence or not and estimated diameter

Their ultrasound criteria:

• Thickness of the endometrium: average of the measurement of each horn in front of the bifurcation
• Diameter of the uterine lumen
• Diameter of ovarian structures (measured with the ultrasound grid and determined from the surface area (S) according to the formula d =√[(4xS)/π]. By cyst is meant a structure with a diameter > 2.25 mm.

A cow was considered   to be inseminated on the following criteria:

• The entire reproductive tract is in the pelvic cavity
• The diameter of the horns is less than 4 fingers
• The two horns are practically symmetrical
• The uterus is firm or tonic
• Presence of fluid is not identified by palpation or uterine lumen diameter is < 10 mm
• The largest follicle present is between 11 and 22.5 mm in diameter and no CJ > 10 mm in diameter is present

THEIR OBSERVATIONS

The % of pregnancy of cows inseminated after manual and ultrasound examination is higher (63%) than that of cows inseminated based on manual examination only (55%). These percentages are higher than those usually observed in dairy cows (< 40%)

Ultrasound examination is more selective than palpation. Indeed, the % of inseminated cows in the “palpated” and “palpated and ultrasounded” groups were 78 and 67% respectively. Ultrasound examination was better at confirming the absence of follicles and corpora lutea > 10 mm in diameter than manual palpation, resulting in fewer cows not inseminated for this reason (19 vs 53%). On the other hand, it is better at confirming the presence of a follicle associated with a corpus luteum. This results in more cows not inseminated for this reason (30 vs. 5%).

Uterine wall thickness was significantly greater in inseminated cows (8.5 mm) than in non-inseminated cows (7.7 mm). Follicle diameter and uterine wall thickness measured by ultrasound had significant effects on % pregnancy (See figure). Uterine wall thickness in endometritis is similar to that of inseminated cows (8.5 mm). However, the sensitivity of ultrasound diagnosis of this condition based on this criterion is only 4%.

The thickness of the uterine wall is proportional to the degree of estrogenic influence and thus to the low progesterone concentration.

IN CONCLUSION

Professionalize the treatment of insemination: perform an ultrasound examination. If no uterine infection, pneumo-urovagina or ovarian cyst is identified, inseminate the cow only after ultrasound confirmation of

• a follicle between 12 and 17.5 mm in diameter
• a uterine wall thickness of less than 9 mm
• no corpus luteum larger than 10 mm in diameter