Learning Reproduction in Farm Animals

Learning Objectives:

To understand what influences the postpartum interval to rebreeding.
To understand how the postpartum period can be managed to reduce the interval from parturition to conception.
 

• Sows; Infertile estrus. 3-10 days postpartum, 1st fertile estrus after weaning.

 

 
 

• Ewes; Non-seasonal ewes. Non-fertile estrus, 21 days postpartum, 40 days to 1st fertile estrus.

 

 
 

• Mares; Foal heat. 5-15 days postpartum (Lower fertility). Next estrus 45 days postpartum.

 

 
 
 

• Cows; 1st estrus: 30-40 days postpartum in dairy cows and 40-60 days in beef cattle.

 

 
 
 

1. Body condition pre and postpartum

 
 
2. Plane of Nutrition

 
 
3. Lactation stress

 
 
4. Suckling stimulus

 
 
5. Photoperiod

 
 
6. Temperature

 
 
7. Presence of male

 

 
 

OSU Condition Scoring System
Score	Description	Photograph
1	Severely emaciated. All ribs and bone structure easily visible  and physically weak. Animals have difficulty standing or  walking. No external fat present by sight or touch.
2	Emaciated. Similar to 1, but not weakened.
3	Very thin. No palpable or visible fat on ribs or brisket.  Individual muscles in the hind quarter are easily visible and  spinuse processes are very apparent.
4	Thin. Ribs and pin bones are easily visible and fat is not  apparent by palpation on ribs or pin bones. Individual  muscles in the hind quarter are apparent.
5	Moderate. Ribs are less apparent than in a 4 and have less than  1/2 cm of fat on them. Last 2-3 ribs can be felt easily (less  then .5 cm of fat). No fat in the brisket. At least 1 cm of fat  can be palpated on pinbones. Individual muscles in hind quarter  are not apparent.
6	Good. Smooth appearance throughtout. Some fat deposition in brisket.  Individual ribs are not visible. About 2 cm of fat on the  pin bones and about 1 cm of fat on last 2-3 ribs.
7	Very Good. Brisket is full, tailhead and pin bones have protruding  deposits of fat on them. Back appears square due to fat. Indentation  over spinal cord due to fat on each side. One to two cm of fat on last  2-3 ribs.
8	Back is very square. Brisket is distended with fat. Large protruding  deposits of fat on tailhead and pin bones. Neck is thick. Three to four  cm of fat on last 2-3 ribs. Large indentation over spinal cord.
9	Very obese. Description of 8 taken to greater extremes.

Nutrition of Beef Cows

Estrus Response
 
 
 

Pregnancy Response:
 
 
 

Calf Performance:
 
 
 

Sows - Normal weaning 15-35 days postpartum
 
 

Weaning   Days Postpartum	Days to Estrus	Litter Size
10	12	10.5
15-21	7	11.5
24	5	11.7

 
 
 

Cattle - Postpartum interval to 1st estrus.

12-74 Days       Dairy cows milked 2x/Day.
 

46-104 Days     Suckled Beef Cows.
 

~14 Days          Mastectomized Cows.
 
 
 

• ­ in tonic LH causes ­ progesterone

 
• Source of progesterone?

 
1. Ovary
2. Adrenal

 
• ­ Progesterone primes the brain

 
1. For behavior estrus

 
2. For surge of LH

 
• - Need a ¯ in progesterone for

 
1. For behavioral estrus

 
2. For LH surge

 
• - With decrease of progesterone, follicular growth and estrogens increase ® LH surge.

 
 
 

• Feed intake of sows (flushing) after weaning helps.

 
• Maintain animals in moderate to good body condition.

 
• Avoid weight loss unless over conditioned.

 
• Early weaning to remove suckling effect

 
• Sows at 15-21 days postpartum

 
• Cows at ~50 days postpartum

 
• Calf separation for 48 hours at 40-50 days postpartum.

 
• Once a day suckling.

 
 

Illustrated Notes

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