英语翻译and positive instead of negative body weightchange resulted when the concentrates fedamounted to about 19 lb per cow daily versusabout 8.5 lb.The Michigan study by Brownet al.(14) showed dramatic increases in milkproduction at higher leve

英语翻译and positive instead of negative body weightchange resulted when the concentrates fedamounted to about 19 lb per cow daily versusabout 8.5 lb.The Michigan study by Brownet al.(14) showed dramatic increases in milkproduction at higher leve
英语翻译
and positive instead of negative body weight
change resulted when the concentrates fed
amounted to about 19 lb per cow daily versus
about 8.5 lb.The Michigan study by Brown
et al.(14) showed dramatic increases in milk
production at higher levels of grain feeding,
especially at the free-choice level.It is of interest
that the cows in both the Michigan and
Washington studies did consume sizable amounts
of forage.Olson and Benson (47) and Charron
(21) also fed grain free-choice.In the latter
(21),a field study,half of the 224 cows involved
reached grain intakes as high as 44 ]b
daily; and 91% of the test animals responded
by producing more milk.On the other hand,
a Florida study (60) indicated little advantage
in providing a supplemental bulky concentrate
in addition to the usual concentrate part of
the ration.Tennessee work (11) showed no
advantage in unlimited grain feeding,but the
productive level of the cows was low.A Nebraska
(54) report failed to show an advantage
for a 17.8% increase in grain intake,although
the increase was offset partly by lower silage
intake.Hooven and Plowman (29) paired two
groups of /9 cows each on the basis of their
first-lactation performance and calving dates.
One group was fed grain,hay,and silage ad
libitum,whereas the controls were fed at 110%
of Morrison's standards for maximum requirements.
No difference in FCM production was
noted; however,the ad lib fed cows did consume
more ENE,apparently converted into
body gains.
A frequently encountered problem resulting
from heavy concentrate feeding centers around
the depression of the fat percentage in the milk
produced.In some of our own work (12) a
significant depression was observed,although
not with respect to all cows.Others have reported
a decrease in milk fat per cent (7,13,
53) as concentrate feeding was increased.
Ronning (52) and Hawldns et al.(25) noted
lower milk fat content when the proportion of
dietary concentrates exceeded 30 or 35%,and
the concentrates were pelleted.Ad lib feeding
of grain resulted in milk fat depression in two
experiments (6,]1),but there was no effect
in another (14).
The composition of the milk fat appears to
be altered when the phenomenon of fat depression
is experienced.Decreases in Reichert-
Missel number (3,22,42,56),and saponification
number (3) have been reported; however,
iodine number has been increased (2,56).Kuns-man and Keeney (35) noted a decrease in saturated
and an increase in the unsaturated fatty
acids of milk fat produced 'by cows on a daily
diet of 3 lb of hay plus grain in ad lib quantities.
There is good evidence that diets which tend
to cause a reduction in milk fat percentage also
tend to rrow the ratio of acetic to propimfic
acids found in rumen contents (7,12,25,27,
50,58).It is tempting to postulate a causeand-
effect relationship between the ratio of
rumen acids and milk fat depression.

英语翻译and positive instead of negative body weightchange resulted when the concentrates fedamounted to about 19 lb per cow daily versusabout 8.5 lb.The Michigan study by Brownet al.(14) showed dramatic increases in milkproduction at higher leve
和积极的而不是消极的体重
变化导致的集中喂养时
为每头奶牛每天大约19磅相比
关于8.5英镑密歇根大学的研究由布朗
等人. （14）显示,牛奶急剧增加
在粮食生产饲养水平,
尤其是在自由选择的水平.这是利益
同时,在密歇根州和牛
华盛顿研究并消耗巨额资金
饲料.奥尔森和本森（47）和查伦
（21）还喂粮食自由选择.在后一种
（21）,实地研究,涉及的224头奶牛的一半
达成粮食摄入量高达44] b
每天,和91％的实验动物反应
通过生产更多的牛奶.另一方面,
佛罗里达州的一个研究（60）表示什么好处
在提供一个庞大的集中补充
除了通常的集中部分
配给.田纳西州的工作（11）无
优势无限粮食喂养,但
在奶牛生产水平较低.阿内布拉斯加
（54）报告没有显示出优势
粮食摄入量为17.8％的增长,虽然
增加部分抵消了较低的青贮
摄入量.胡文和普洛曼（29）配对2
作者/ 9组,每组头奶牛的基础上的
第一产奶性能和产犊日期.
其中一组喂粮食,干草,青贮和广告
自由采食,而对照组饲喂110％
莫里森的最高要求的标准.
流式细胞仪生产无差异
指出,然而,即兴消费喂养奶牛没有
更多的东东,显然转换成
身体的收益.
一个经常遇到的问题造成
从沉重的集中供餐中心附近
在对乳脂率抑郁症
生产.在我们自己的工作（12）1部分
重要的是抑郁症的观察,虽然
没有对所有牛.其他报道
在脂肪减少百分之牛奶（7,13,
53）为集中饲养增加.
罗宁（52）和Hawldns等. （25）指出
牛奶脂肪含量较低的比例时,
饮食精矿超过30或35％,而
在集中进行造粒.即兴喂养
粮食导致牛奶中的脂肪在两个抑郁症
实验（6,] 1）,但是没有效果
在另一个（14）.
牛奶脂肪的成分似乎
更改时,脂肪抑郁现象
有经验.在下跌赖克特-
米塞尔数（3,22,42,56）,和皂化
数量（3）已报告,但是,
碘的人数已增加（2 56）. Kuns人与基尼（35）指出,在减少饱和
并增加了不饱和脂肪酸
酸的产生奶牛每天对牛奶脂肪
3磅的干草饲料粮食加在即兴数量.
有很好的证据表明,饮食往往
为减少导致牛奶中的脂肪百分比也
往往为N〜rrow的醋酸,以propimfic比例
发现瘤胃氨基酸含量（7,12,25,27,
50,58）.这是一个诱人的假设causeand -
效果之间的比例关系
瘤胃氨基酸和脂肪牛奶抑郁症.