Page 120 - Calculating Agriculture Cover 20191124 STUDENT - A

11-8 Large Animal: Beef, Swine and Sheep CH 11]

DAIRY CALF PRODUCTION
When breeding, it is anticipated that the likelihood a male will be born is 50%. However, in the
dairy industry their breeding bulls are evaluated by the number of daughters that they sire and the
likelihood a daughter will be born. The reason that higher female birth rates are desired is because the
female produces milk and it is the milk production with butterfat content that generates revenue to the
dairyman. Heifers are also important for replenishing the dairy herd. Bull calves that are born are
often raised for veil and sold off. It is the heifer crop that is important.

Example: During the year there were 552 calves born and of those 310 were heifers in a dairy of
600 cows. (a) Calculate the percent of calf crop. (b) Determine the percent heifer crop.
(c) Calculate the bull crop.

Solution:
(a) # calves birthed / dams calving x 100% = % production per species
_______ % calf crop
552 / 600 x 100% = 0.92 x 100% = 92% calf crop

(b) # heifers birthed / dams calving x 100% = % production per gender
______ % heifer crop
310 / 600 x 100% = 0.516 x 100% = 51.6% heifer crop

(c) # of calves − # of heifers
% bull crop = —————————— x 100%
# of cows
_______ % bull crop

552 − 310
Farm Flock % bull crop = ———— x 100%
(sheep): Numbers 600
of animals varying 242
in size from a few = ——- x 100%
head to 500 head 600
which would be a = 0.403 x 100%
Large Farm Flock.
% bull crop = 40.3 %

Range Band
(sheep): The size Sheep Production
of a band is The revenue sources from sheep are wool, meat and breeding. The dominant revenue with sheep
determined by the is the meat which means that lamb production needs to be high. As ewes will often twin it is possible
number of sheep to have a lamb crop that is greater than 100%. To realize high lambing rates requires healthy ewes
that can be and productive rams. A ram can service 3 to 4 ewes per day, with a recommended ratio of mature
efficiently handled rams that varies from 1:35 to 1:60. With large farm flocks or range bands the percentage of rams to
by one man. This ewes is often higher reaching 1:100. But for calculations, using a ratio of 1:35 and the ram servicing
will vary according 4 ewes per day means that the ram will impregnate 35 ewes in (35 ewes ÷ 4 ewes/day = ) 9.5 days or
to (1) the season 10 days. With a ratio of 1:60 it will take (60 ewes ÷ 4 ewes/day = ) 15 days for the ram to the ewes.
of the year, (2) the
topography of the Most sheep are seasonally polyestrus and short-day breeders. They will begin exhibiting estrus
country and type of when length of day begins decreasing. Ewes come into heat every 16 to 17 days until they are bred or
vegetation, and (3) return to anestrus. Thus, the most natural time for sheep to breed in the U.S. and Canada is the fall
whether the ewes (Oct-Nov).
are dry, lambing, A ram lamb at 5 months of age will settle some ewes, but he will be a better breeder at 7 or 8
or suckling. Range months of age. As a general rule, ram lambs should be 50 to 60 percent of their mature weight before
bands vary from being used for breeding. Mature weight is dependent on the breed.
800 head to 3,500 It is commonplace for some producers to breed well-grown ewe lambs when they are 7 to 9
head.
months of age. Other producers wait until their ewes are 18 months old before breeding them to lamb
as 2 year olds. The length of gestation for sheep is 152 days.

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