Factors affecting animal performance during the grazing season in a mountain
cattle production system.
In the past, many different systems of suckler cattle have been examined, trying to
determine the best seasonal dates for calving and weaning. Individuals have been looking
at gestation lengths for a period of time and trying to better understand calving ease and
the amount of time needed to recover and breed back. Scientists chose this particular
observation because farmers in high elevation areas were interested in management and
animal factors that affected performance of certain breeds of cows (i.e. grazing
performance & calving seasons).
Researchers are attempting to associate variables, such as weight gain, effects of
calving season, and breed to determine the animals’ performance on particular pastures,
whether in high altitude or sea level. This topic is important to understand the
relationship between grazing seasons and calving opportunities so that farmers can
maximize their animal production each season.
The scientists were looking to correlate specific species of cows with better
animal performance (i.e. calving season, grazing performance on the different types of
pastures; forest pastures & high elevation pastures).
Materials and Methods
Researchers were analyzing and recording observations of the different species
and their performances during each grazing season in suckler cattle herds. It is important
to note that the data of cows was kept only if each individual cow calved in 2 consecutive
years. They divided the herd into two groups. Group A consisted of both Brown Swiss
and Pirenaica cows, they calved in the spring (Feb-May), which is traditional for the area
(Spanish mountains). Also Group A was loosely housed (mid-Dec.-to mid-June).
Group B consisted only of Brown Swiss; they calved in the autumn (Sept-Dec), housed
throughout lactation.
After keeping the groups separated and allowing them to graze in different
seasons, they bred them by natural service with bulls of consistent breed. They would
group feed during the indoor period, taking samples throughout the entire period for
chemical analysis. The last two years they used a different mixed ration of food to
observe any change in animal performance. Another important test was studying the
effects of different feeding techniques and comparing these to nutritional levels and
reproductive rates during the indoor housing periods.
Researchers weighed the cows multiple times throughout the years and aimed to
examine the performances independently of causes such as pregnancy and digestive
content. They had a 6% change of live weight from dry to green diet. The variation
between groups was dependent upon the year and the amount of rainfall/ temperature
gradient. The scientists were surprised by the different results between breeds varying
from the spring to autumn season.
The information was significant meeting expectations from the hypothesis. The
variation between animal productions based on breed was observed and measured.
According to the article, “The choice of one or the other (breed), should be based on
other more differentiating criteria, such as their degree of adaptation to high mountain
conditions or meat and carcass quality of the products” (Casasu’s et al. 1649).
The researchers noticed that the “year” was something of interest seeing a
variation in the weight of the cows. They came to the conclusion that this variation could
be correlated to the weather and other factors that are uncontrollable in nature.
Casasus, I., A. Sanz, D. Villalba, R. Ferrer, and R. Revilla. "Factors Affecting Animal
Performance during the Grazing Season in a Mountain Cattle Production
System." Journal of Animal Science 0021.8812 (2002): 1638-651. Web. 10
Sept. 2014.