| Summary: | The quality of water in Saskatchewan is less than ideal and
poor water quality can affect livestock adversely. The sulfate
content of the water can affect ruminants by interfering with Cu
metabolism. other factors such as Zn, Fe and Mo content of the
feed can also have an effect on cu metabolism. For these reasons
two surveys were undertaken to investigate the source and quality
of water on Saskatchewan dairy farms and the effect of this water
on dairy cattle.
Survey One found that 92.8% of the 656 farms used the
Holstein breed of dairy cow with an average milking herd size of
42 cows. Average milk production for Holsteins was 20.5 kg d-1.
Other breeds used included Brown Swiss (0.2% of farms) producing
19.2 kg cow-1d-1, mixed breed herds (4.3% of farms) producing
18.8 kg cow-1d-1, Ayrshires (1.7% of farms) producing 18.4 kg
cow-1d-1, and Jerseys (1.0% of farms) producing 13.9 kg cow-1d-1.
39% of the farms surveyed used either DRAS or ROP milk recording
programs.
Water quality and water sources varied throughout the
province. The average well depth was 148.2 meters with 84.4% of
farms using water from wells. Other sources of water included
dugouts, springs, reservoirs and treated city water. The average
water on Saskatchewan dairy farms contained 750.7 mg 1-1
hardness, 595.9 mg 1-1 sulfate, 22.8 mg 1-1 nitrates and 1971.4
S cm-1 conductivity. 76.7% of farms had water hardness levels
less than 1000 mg 1-1. 81.8% of farms had water sulfate levels
of less than 1000 mg 1-1• 83.3% of farms had water nitrate
levels of less than the maximum recommended level for livestock
of 22 mg 1-1, however, 28 farms (4.2%) had nitrate levels of
greater than 100 mg 1-1• 60.4% of farms had water conductivity
levels of between 1000 and 3000 S cm-1. The levels of
constituents in the water varied significantly with well depth in
accordance with accepted theory on the chemical development of
aquifer water. While the average water appears to be of
reasonable quality there was a wide range of constituent levels
that varied greatly between farms.
stepwise regression found a small but significant negative
effect of hardness on milk production (r2 = 0.0158, P < 0.01).
In the second survey 12 farms were selected on the basis of
water sulfate level, record-keeping to provide a wide range of
water sulfate levels and allow accurate measurement of cow milk
production and reproduction.
The average water on farms in Survey Two contained 727.6 mg
1-1 hardness, 816.4 mg 1-1 sulfate, 5.9 mg 1-1 nitrates, 2313.3
S cm-1 conductivity, 396.3 mg 1-1 alkalinity, 148.2 mg 1-1 Ca,
31.6 mg 1-1 Mg, 320 mg 1-1 Na and had a pH of 7.3. Farms were
chosen to provide a wide range of water sulfate levels and thus
water sulfate ranged from 84 mg 1-1 to 2220 mg 1-1.
Average 4% FCM production in Survey Two was 31.7 kg cow-
1day-1. Stepwise regression found that 4% FCM production was
significantly affected by DMI and Days in Milk (r2 = 0.28, P <
0.01) but not significantly affected by the intakes of protein,
nitrates, sulfur, Cu, Zn and Fe. Correlation analysis indicated
significant correlations between 4% FCM production and hardness,
sulfates, nitrates and Ca levels in the water. Stepwise
regression using 4% FCM production and water quality parameters
found that nitrates had a negative effects on production (r2 =
0.14, P < 0.05).
This survey indicated that cows could receive from 1.4 to
43% of their Ca requirements from Ca in the water. Cows can also
receive from 5.8 to 62.8% of their daily S intake from S in the
water. Na in the water can account for 6.6 to 288% of the cow's
Na requirement.
CU status, as measured by plasma CU content, was found to be
correlated to Mo intake, Days in Milk and Services per
conception. There was not significant correlation between plasma
Cu and Total S intake however, there was significant positive
correlation between S intake and serum K, glucose, CPK, and
significant negative correlation between S intake and serum urea.
Total S intake was not significantly correlated to other serum
parameters.
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