How much grass and feed does a cow need per day, and how do you identify estrus and pregnancy?

A cow refers to a female bovine. It can produce milk and can bear offspring. So how much grass and feed does a cow usually need to be fed per day? How are estrus and pregnancy identified (recognized)?

How much grass and feed does a cow need to be fed per day?

A cow's feed intake, calculated on a dry matter basis, should be 1.5% of its body weight.

1. Whether forage or concentrate, both contain a certain amount of moisture. In production practice, cows of different breeds, or cows of the same breed in different seasons, also have different feed intakes, so the cow's feeding situation must be grasped according to local conditions.

2. The supplementary feeding of concentrate to cows must be determined according to the animal's body size, body condition, pregnancy, lactation and other conditions.

(1) For a non-pregnant cow, the amount of supplementary concentrate is determined by body condition, generally 0.5-1kg per day.

(2) For a cow after 2 months of pregnancy and for 2 months after calving, supplement 1-2kg of concentrate per day.

3. For feeding cows, the principle of roughage first and concentrate afterward, and feeding first and watering afterward, must be followed. In winter, they can be fed 2 times per day, and given warm water after feeding; in summer, feed 3 times per day. Concentrate should be mixed into a blended feed according to schedule and proportion, mixed evenly, moistened with water 6—8h before feeding, and after it has softened, mixed into the feed and given. At each feeding, the keeper should feed according to the trough, adjust the surplus and shortage, fill as they eat, and ensure they eat their fill in one go. Feed varieties should be relatively stable, and all kinds of feed should be fed in combination; do not constantly change them. If replacement is necessary, it must be done gradually, so that the cow gradually adapts and normal digestion is ensured. Do not feed moldy, spoiled or frozen feed. In winter, silage should be fed inside the barn, taking it out as it is fed.

How are cow estrus and pregnancy identified (recognized)?

Estrus:

(1) Estrus

1. Estrous cycle: the period from the beginning of the first estrus to the beginning of the second estrus is called one estrous cycle. One estrous cycle is 18-21 days, with an average of 20 days. The estrous cycle includes proestrus, estrus, metestrus and diestrus. Estrus is also called the duration of estrus; the period from the start of estrus to the stop of estrus is called estrus. For dairy cows and yellow cattle it is generally 6-36 hours, with an average of 18 hours; for water buffalo 6-8 hours. The duration is longer in warm seasons and shorter in cold seasons.

2. After a cow reaches sexual maturity, in the cyclic cycle there are four physiological characteristics: vulvar changes, sexual excitement, sexual desire, and ovulation. The externally observable phenomena such as vulvar changes, sexual excitement and sexual desire are called estrus. Accurately grasping the objective laws of cow estrus is the key measure for carrying out breeding and raising the conception rate. Cow estrus has the following changes:

(1) Behavioral changes: sexual excitement is the abnormal whole-body mental state shown by a cow during estrus. At this time, the cow is more sensitive than usual, bellows restlessly, often raises and swings its tail, has reduced appetite, and wanders about. The intensity of sexual excitement is stronger in young cows than in old cows. Mounting is a manifestation of a cow's sexual desire; a cow in estrus often mounts other cows or is mounted by other cows. When an estrous cow mounts other cows, it often dribbles urine and makes a low, short grunting sound; this phenomenon is more pronounced in young cattle.

(2) Vulvar changes: starting from proestrus, the vulva goes from slightly swollen to gradually full, soft and relaxed, and the labial mucosa is congested, flushed and glossy; after ovulation, the vulvar swelling subsides, shrinks and shows wrinkles, and the vaginal mucosal congestion and flushing subside and become pale. Two hours before sexual desire appears, mucus begins to flow out from the vagina, and a small amount of blood streaks is often attached to it. The mucus discharged at the end is relatively clear and transparent, like egg white, flowing out in a thread-like manner, elastic, and can be stretched into long strands, commonly known as “hanging thread”. Before ovulation, the discharged mucus gradually becomes white and thick.

(2) Estrus identification

Based on the changes in the two aspects discussed above, judge whether the cow is in estrus and whether the estrus period is in the early, peak or late stage, and find the best breeding time.

1. Proestrus: bellowing, restlessness, fond of walking about, sensitive to external reactions; the vulva begins to swell, is soft and relaxed, the mucosa is flushed, congested and glossy; a small amount of mucus flows in the vagina, and the vaginal mucosa is congested; it likes to sniff other cows' vulvas and mounts other cows; when mounted by other cows it is very quiet, stands still, and looks back with its head.

2. Peak estrus: sexual impulse is active; when mounting other cows it acts like a bull in impulsive mating posture; it is mounted by other cows many times; vulvar changes are relatively more obvious than in the early stage; the mucus flowing from the vulva is more transparent and forms very long threads; appetite is abnormal and milk production declines.

3. Late estrus: the cow turns from excitement to quiet, neither mounts other cows nor allows other cows to mount it; it mostly lies down to rest, and the vulva returns to normal.

Ovulation is the sign of the end of estrus. Ovulation occurs 18 hours after the end of sexual desire, mostly between 22:00 at night and 3:00 in the morning.

(3) Abnormal estrus

When certain factors make cow estrus exceed the normal laws, it is called abnormal estrus.

1. Silent estrus: the cow lacks manifestations of sexual desire during estrus. The cause is malnutrition, insufficient secretion of follicle-stimulating hormone or estrogen, mostly caused by long-term housing.

2. False estrus: one type is the sexual desire shown by a pregnant cow at “more than half of gestation” (around 5 months); the other is in growing heifers with ovarian insufficiency and cows with endometritis, where the estrus manifestations are normal but there are no developing follicles in the ovary.

3. Anestrus: malnutrition, ovarian and uterine diseases, etc., often cause cows not to come into estrus.

4. Continuous estrus: the number of estrus days is long, or intermittent. This is mainly caused by ovarian cysts and alternating follicle development, or by excessive estrogen production or alternating estrogen production.

Pregnancy:

1. Identification by looking at the cow's eyes.

On the iris directly above the pupil of a pregnant cow, 3 particularly conspicuous vertical blood vessels appear, the so-called pregnancy blood vessels, which are filled and raised on the iris surface and are purplish red. On the iris of a non-pregnant cow, the blood vessels are fine and not conspicuous.

2. Identification by looking at the udder.

A swollen udder and hard, straight teats indicate a pregnant cow. If the udder is not swollen and the teats are not hard and straight, then it is not pregnant.

3. Identification by looking at the oral cavity.

Open the cow's mouth and look at the sublingual caruncles on both sides of the mouth. If they are bright red, it is a pregnant cow; if they are pink or pale red, then the cow is not pregnant.

4. Identification by looking at the tail.

When the cow's tail hangs down without swinging, if it covers the vulva and is placed obliquely to the left or right, it indicates the cow is pregnant. If the tail hangs straight down covering the middle, it indicates it is not pregnant.

5. Identification by looking at the milk.

If the milk squeezed out by hand is honey-colored and paste-like and does not flow, then it is mostly a pregnant cow; if it is white and thin and flows out naturally when squeezed, then it is an empty (non-pregnant) cow.