inseminations needed for fertilisation decrease due to the im- provement in the general health of the animal which results from the increased levels of calcium, phosphorus, vitamin A and vitamin D in the blood, as well as increasing the propor- tion of protein, hemoglobin, and red blood cells. These bene- fits may not be achieved only by prolonging the photoperiod, but the intensity of light should also be taken into account. It was found that increasing the intensity of light above 150 lux may adversely affect the immune response and infection of the animal with diseases such as mastitis and metritis may then occur.
4. Floor-type In a study conducted at the University of Hohenheim in Ger-
many, it was found that covering the floors of the barns with sheets of soft rubber that mimics the soil of the pastures helps to achieve a number of advantages including increas- ing the efficiency of oestrus detection by increasing the mounting rates, while in the case of hard floors these rates are lower due to the fear of slipping.
5. Noise Noise may be generated by several means such as the electric
generators, pumps, and/or other machines used in the farm. Chronic noise stress (100 dB or above) also affects the male sex hormone and produces changes in the reproductive or- gans and glands. Noise stress provokes an increase in serum corticosteroid, which causes up to an 80% decline in testos- terone concentration. Low testosterone production adversely affects the quality of ejaculates and subsequent fertility. The decrease in testosterone levels is also associated with a
marked reduction in epididymis sperm numbers. Moreover, the epididymis sperms are agglutinated upon exposure to noise and the number of dead sperm also increases. Such changes are in most cases irreversible and noise-induced in- fertility may thus last for the entire reproductive cycle of the male animals. The effects of noise on the reproductive functions of females have not yet been established, but a great deal of work has been done in this area on laboratory animals. The ovaries and the uterus diminished significantly in female rats after a noise exposure of 110 dB for five minutes 15 times per day for 11 days at 375-500 Hz. Remaining oestrus occurs after noise exposure as well. An increase in abortion frequency and re- duction of foetus weight have been also registered. Much of the noise effects can be alleviated by the installation of reso- nators or exterior application of sound barriers. Also, consul- tation with a qualified acoustical engineer can lead to specific solutions for most noise problems.
6. High altitude Fertility is affected in male animals, especially in cattle and to
a lesser extent in sheep, after transporting them to high alti- tudes and after living there over a few months. The testicles become atrophied and the germinal epithelium is replaced by connective tissues. These changed produce infertility which usually disappears in several months if the animals are brought down to sea level. Female fertility, on the other hand, is not affected and animals show normal oestrus cycles and have normal lambing/calving percentages.
References are available from the author upon request. ▶DAIRY GLOBAL | Volume 7, No. 1, 2020 15
Noise stress can impact both male and female cows.
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