ISRAEL JOURNAL OF
VETERINARY MEDICINE
FERTILITY IN DAIRY FARM MANAGEMENT - A SUMMARY OF THE
WORK OF THE LATE DR. CHAIM STURMAN
Zeron Y
Sion, Company for Artificial Insemination, Israel
In recent years, there have been advances in many areas of applied genetics, so that it
is now possible to give answers arising from cattle breeding at the level of a single
gene by applying new technologies.
We are witnessing a rise in the average milk production per cow, and countries
working according to production quotas are seeing a drop in cow numbers. In
addition, cow fertility remains a perpetual problem that is difficult to predict. Studies
provide partial solutions which help some farms but are of less use to others.This is
primarily because the fertility of a specific herd is influenced by many factors:
SEASON-summer and fall as opposed to winter, changes in breeding schedules for
summer milk production.
COW HEALTH-metabolic problems after calving, uterine infections, mastitis etc.
CALVING-dry period length, ease of calving, twins, calf size, length of
pregnancy,sex of offspring.
FEEDING-negative energy balance, body condition, ration ingredients and the interrelationships, minerals and microelements.
HEAT OBSERVATION MANAGEMENT-pedometer adjustment, visual
observation, staff management and synchronization.
MILK PRODUCTION-high producing compared with low producing cows.
HOUSING MANAGEMENT —ventilation and cooling area per cow, cow shed
height, stalls or open shed, manure pack, cement alleyway, footing surface.
GENETICS-bull-daughter fertility, bull fertility.
The herd fertility level is the outcome of the interaction of all these factors, and an
improved understanding the way to deal with fertility problems. The problems may be
similar in any two herds but the solutions may differ because of different factor
interactions in each herd.
Dr. Chaim Sturman together with researchers at the Israel Herdbook and the
veterinary community have specialized in expressing fertility characteristics and risk
factors in reports that enabled extension workers and dairymen to define the
individual problems for each farm. Such reports are used to provide the basis for
studies and summaries right up to the present day.
In this survey we will focus on some of the factors that affect fertility which Dr.
Sturman worked on, and which became the basis for continuing study over the years.
LENGTH OF THE HEAT CYCLE - It is generally accepted that the normal heat
cycle is 22 days for cows and 21 days for heifers. In comparing heat cycles of the
"ON" (Israel) and "Megle" (Germany) breeding associations, Bar Anan found a very
similar cycle length. However, from the daily variation of the breedings of the same
cows, it was found that in the first cycle more than half the breedings were over the
average (22 days), in the second cycle the norm matched the average (42 days), and in
the third cycle more than half the breedings were less than average (63 days). In
additional studies (1) cycle length was compared with and without breeding, and it
was found that cycles after breeding were longer by 1.2 days. The data suggested that
many of the return breeders have longer cycles because of early embryo death. In
response to these findings, Nir and Sturman determined days between normal and
double cycles and the liklihood that cows would be presented for insemenation after
first breeding (2).
The breeding behavior varies as a result of early embryonic death, cysts,
nymphomania, permanent corpus luteum, and inactive ovaries. Moreover, inadequate
or unprofessional observations or poorly adjusted parameters in pedometer systems
can result in cows not being presented for breeding at the optimal time.
Synchronization protocols combined with conventional heat detection can negatively
affect the distribution of days between breeding.
In Table I we present the large difference between 1990 and 2005. This probably
results from the greatly increased use of pedometer systems which enable much
greater accuracy in detecting heats.
The different cycles are diagnosed according to: Double breedings ; two breedings,
one after the other within four days which are considered as one breeding cycle, both
statistically and with respect to payment short cycle represents either a"physiological
error" of the cow or a mistake by the farmer and the inseminator at one of the
inseminations, cow not in heat.
Normal cycle ; most of the heats when the cow didn't conceive at the previous
insemination.
Long cycle; irregularity in the sex cycle of the cow, possible embryo death or a
mistake in heat indentification at one of the heats.
Double cycle ; explained one unobserved heat.
During his farm visits Chaim Sturman emphasized the importance of heat cycle
distribution and using this information to understand the source of the problem of
timing of breeding.
Rejections — Cows bred when not in heat can be damaged in various ways:
Wounding and infections resulting from forced entry into the uterus.
Embryo death. Distorting the follow up after a normal sex cycle.
Mistaken date of conception after a successful insemination.
In the 1970's data on the connection between progesterone levels in milk and the sex
cycle became available. It was found that 16%-20% of the cows presented to AI were
not in heat and had high levels of progesterone in their milk. Conception rates of these
cows were very low (3). In a farm survey carried out between 1975-1978 it was found
that by categorising the rejections as days from conception the percentage of
rejections was higher by 30% in the range of a normal cycle, 17-25% for short cycles,
while long and double cycles were about 18% each. In examining the hormone levels,
a lowering of progesterone concentration, rise in estrogen and a small rise in LH
concentration was found in rejected cows (results similar to the cycle of a nonpregnant cow). After examing the reasons for the rejections, Sturman constructed a
table (Table 2) that sorted rejections into four categories:
Correct rejection, mistaken, in doubt and rejections that should not be included in the
analysis.
It was found that about 8% of cows presented were not in heat and about 12% of
pregnant cows were brought to the inseminator at least once during their pregnancy.
Most were in the 48 days after conception and many of the false heats were at normal
or double cycle intervals. In all the parameters heifers are more problematical than
cows. These figures prompted researchers and primarily Dr. Sturman to study the
level of damage to pregnant cows bred by mistake. The figures indicate that 50-80%
embryo death in cows bred a second time till a pregancy check at 50 days. This is
very important since it was found that 50% of the correct inseminator rejections were
in pregnant cows and heifers. The inseminator rejection protocol is unique for Israel
and is now part of the normal routine of all artifical inseminators and dairy herdsmen.
Difficult calvings. Calf deaths at birth represent serious losses for farms. Cows
suffering a difficult calving tend to give less milk and have lower fertility. Bar Anan
has investigated this problem, and today dairyman choose sires with easy calving
traits especially for calves. In December 1994, Sturman and Ezra published a study
analyzing the factors influencing difficult calvings and calving mortality in Israeli
dairy herds (4). It was found that the four main factors influencing the rate of hard
calvings and deaths at birth are the farm, conditions (ration, disease, buildings,
crowding in the calving area and climate), sire of the calf and sire of the mother. The
influence of the calving environment is equivalent to the combined effect of the sires,
breeding bull and maternal sire together. Sturman and Ezra found that there were
differences of up to 16% between easy calving and hard calving sires and that these
differences strongly affected the calf death rate. In other words, using bulls with the
genetic trait of easy calving strongly affected an entire year's calf crop. However
using easy calving bulls sometimes resulted in calves with low genetic potential so
that they could leave the herd soon after calving. In recent years we have seen better
use of more "neutral" bulls for calving ease. However, because of significant
improvements in the calving environment,and primarily of the rations, the death rate
is reasonable at 7-8%, and the calves have a good genetic potential. Use of
appropriate bulls has a significant effect on heifer fertility. A too short waiting period
after a difficult calving results in a lower conception rate for the first breeding. In the
past, studies in the U.S. showed a negative correlation between mortality rates of
heifers of the breeding bull and that of the same bull's daughters. In Israel it was
found the relationship is positive beween the inseminating bull and his daughters.
Today this trait is published on the "bull board" and dairymen use easy calving bulls
on calves knowing the future effect on the fertitly of the herd.
Palm terminal Timely reports of feritily events are the heart of any system concerned
with herd fertility. For about 20 years the herdbook has been collating herd breeding
data through the Palm terminal. The technology of the Palm terminal and its features
have changed over the years but the direct flow of information without additional
typing contributed to the accuracy of the system and saved manpower. Sturman saw
the great importance of the reliable flow of breeding data for analyses in the
herdbook, so he initiated the Palm terminal first in the area served by "ON" and later
in the "SHERUT" area, and improved the absorption of data directly from the field for
application in fertility analysis. The picture is completed with farm reports on the
cows including pregnancy checks, abortions, veterinary treatments, calvings and
leaving the herd. All these data made it possible to build reports which enable the
dairymen and their advisors to analyze herd fertility in the best possible way. The
reports have been improved over the years but the basis was established by Sturman
and his associates in the herd book and the veterinary profession.
The reports cover several central points.:
1. Voluntary waiting period (VWP).
2. Implementation of first breeding in relation to the VWP.
3. % Conception for each breeding.
4. Heat detection.
5. Additional factors including rejections, induced heats, open days, wasted days.
Another important advantage of Palm terminal for the inseminators work is that it
helps prevent inbreeding. Israel's dairy herd has a low % of inbreeding (despite a
small population and a limited number of family lines), primarily because of the
correct use of the Palm terminal by the breeding technicians. Today there are
computer programs to deal with this problem but the Palm terminal remains the prime
tool in preventing inbreeding.
References:
1. Eged S., Shindler H., Itamar E. Distribution of inter-insemination intervals. Meshek Habackar
v'Hachalav, 233, 25,1991® (in Hebrew).
2. Nir O., Sturman H., Distribution of inter-insemination intervals. Meshek Habackar v'Hachalav, 233,
23-27, 1991.(in Hebrew).
3. Sturman H., Becker A., Ben Shmuel T. Incidence of the insemination of non-oestral dairy cows and
an estimate of ensuing damage. Hekre v'Ma'as 2, 3-23,1980. (in Hebrew).
4. Sturman H., Ezra E., Analysis of embryonic mortality in the last decade. Meshek Habackar
v'Hachalav, 253, 21-29, 1994. (in Hebrew).
5. Aizenbud E., Zaron Y., Ezra Y., Dr. H.Sturman's "The inseminator's rejections". Meshek Habackar
v'Hachalav. 305, 9-14, 2003. (in Hebrew)
6. Sturman, H. Oltenacu, E.A.B. and Foote R.H., Importance of inseminating only cows in estrus.
Sturman, H. Oltenacu, Theriogenology 53 (8), 1657-1667, 2000.