Page 322 - The Welfare of Cattle

daIrY CoW WeLfare and herd turnoVer rates 299

Reproductive failure is a huge risk factor for exiting the herd. To maintain production levels
across a cow’s lifetime requires her to calve at a regular interval. Lower producing cows need to
calve more often than higher producing cows to remain in the herd because they reach lower levels
of production later in lactation and don’t maintain income over operational costs. Reproduction as
a reason for removal include: cattle that got pregnant too long after the previous calving to sustain
the required production until 60 days before the next calving; cattle that got pregnant within the
required time period but aborted the calf; and cattle that didn’t get pregnant. Pinedo shows first and
second lactation animals had higher frequency distributions for removals associated with reproduc-
tion, indicating an area in need of management’s attention. It’s interesting that for pregnant cows
in this study reproduction was the second highest frequency reported for exiting the herd. This
only makes senses if these cows aborted and were open but the abortion was not reported, or they
got pregnant very late in their lactation. Hadley found cows that were pregnant had one half to one
fourth the risk of exiting the herd compared to open cows.
Pinedo et al. reported reproduction as the most often used disposal code noted for intermediate-
and high-producing cows. Hadley’s study conflicts with Pinedo’s showing cows enjoying lower risk
of removal if they delivered higher than average milk production, higher than average protein con-
tent, and higher than average milk persistency. High-producing cows do need extra time to get into
positive energy balance following calving and that can impact reproductive performance. They also
have a longer time from calving to when their production reaches the level where expenses exceed
costs of production. This means they can calve less frequently and still be of economic value in the
herd. More information is needed to understand the reasons for the conflicting reports.
Mastitis is commonly discussed welfare issue brought to the forefront from the use of rBST
to promote milk yields. Mastitis was reported by 99.7% of producers surveyed in 2013 by USDA
NAHMS survey, and about 25% of cows were reported to have a case of clinical mastitis with no
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difference in the percentage of cases reported in small vs. large herds. Mastitis is a general term
that reflects environmental causes associated sanitation, especially in bedding areas and prior to
milking, and contagious causes associated with an infected cow transmitting the bacterial agent
to a noninfected cow usually during the milking process. Mastitis can be painful and is a welfare
concern. An SCC is a laboratory test that can provide some insight into the level of inflammation
in the udder and serves as a proxy for subclinical mastitis. Many studies show animals with high
SCC’s are at higher risk of removal, produce less milk, and have a greater incidence of clinical mas-
titis. Bedding with non-organic materials that don’t support microbial growth and excellent milk-
ing hygiene are important strategies for preventing mastitis. Dry cow treatment and bedding along
with investments in milking equipment offer some additional preventative benefits. While only a
small percentage of mastitis pathogens cause severe and even life-threatening illness, because the
frequency of mastitis occurrence is high this disease accounts a high percentage of on-farm deaths.
A study of SCC’s in 3,000 dairies in Wisconsin showed similar mastitis levels across all herd sizes.
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Pinedo et al. and Hadley et al. reported similar risks of live removal for low production and mastitis
in their studies.
Foot disorders are among the easiest identified welfare concern in today’s dairy enterprise.
Unfortunately, the terms “lameness” and “feet and legs” lack specificity, combining many potential
problems all with different causes and preventions. The prevalence of lameness has been associated
with lactation number, hoof-trimming frequency, walking surfaces, and stall design/comfort, and
has been growing across time. In 2002, the reported prevalence of lameness in heifers was 36.5%,
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and in 2007 it was 58.7%. Flooring is an important factor and efforts to find kinder and safer foot-
ing is ongoing. The average dairy facility in the country was constructed in 1976 so we have older
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technology still dominating our physical plants. A 2010 study showed no association between feet
and leg problems and high production. 21
Pinedo et al. reported a risk of removal for feet and legs reasons about twice that of Hadley,
while removals for udder reasons were similar. Pinedo identified a relationship between removal for