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The pros and cons of late-spring calving

A growing trend has developed among beef producers who raise cattle in the snow belt. Many cow-calf ranchers have adjusted the calving season until much of the snow has melted and the first green blades of grass have shot up. For many late-spring advocates, there just seems to be something natural about allowing beef cows to give birth on pasture instead of in a drylot pens. The practice also supports a substantial cost savings by calving the cow herd on pasture.

Consider the potential savings for a 250-beef cow operation by replacing all the drylot forages and half of the supplemented barley grain in a drylot lactation ration with one month of grazed May pasture. The grass pastures in late spring contain enough forage volume (dry-matter basis) to support the cow herd’s general feed intake and contain early vegetative growth of substantial energy and protein value (note: some barley might be fed on pasture to meet all energy needs).

Big savings

The calculations for potential savings of a late-spring calving season for a 250-head herd are as follows:

  •  Total feed intake of 15 kg = 600 kg x 2.5 per cent of body weight, 15 kg = 14 kg of mixed hay @ $60/mt + 1 kg of barley @ $200/mt.
  •  One month winter feed cost = $ 0.84 + $0.20 or $ 1.04 x 30 days.
  •  Total monthly feed cost savings (250 cows) = $ 7,800.

With these significant savings, remember turning cows out to calve on pasture is only part of the overall feeding program. Consequently, the following practical suggestions should be implemented in a late-spring calving cow herd:

  •  Maintain good cow body condition score for breeding. Cows achieving a BCS of 2.5 to 3.0 had fewer days to first estrus, greater signs of estrus and higher rates of conception, while calves born to these optimal cows had lower pre-weaned mortality rates, and achieved higher weaning weights of 50 to 60 lbs. at the end of the pasture season. In contrast, thin cows (BCS < 2.0) have been known to have delayed first service conception and their newborn calves tend to be less thrifty.
  •  Achieve optimum trace mineral status — copper, zinc, manganese and selenium are particularly important for good beef cow immunity/health, fertility and basic body functions. Too often, they are either low or marginally deficient in soils/cattle forages or are bound up by antagonistic elements. The best nutritional remedy is to feed a well-balanced commercial beef mineral in order to keep cows healthy and help them return to good re-breeding performance.
  •  Implement a creep feeding program. On average, weaned calves from a spring calving operation weigh about 100 lbs. less than winter-born counterparts at any comparable time. Therefore, it makes sense to provide a nutritious calf creep feed on pasture through the summer. It allows late-spring calves to play some “catch-up” with earlier calves and supplies nutrients when milk production from cows slows down.
  •  Provide TLC to first-calf beef heifers. Without the interference of very cold weather, putting late-spring first-calf heifers on a high plane of nutrition allows them to grow and might allow thin animals to put on some critical body condition. Assuring they are in proper body condition helps them achieve better rebreeding success.

Challenges

Aside from the potential winter-feed savings and not having to calve the herd during very cold weather, a late-spring calving season is not without its natural challenges.

For one thing; unexpected spring snowstorms and cold rains can chill newborn calves, which are particularly vulnerable to pneumonia. Similarly, frequent muddy conditions and thawed manure piles provide a catalyst for contagious intestinal scours that could lead to high calf mortality. Fortunately, most spring calves can remain healthy if their mothers are able to escape poor spring weather by going into shelter such as a pole barn with lots of clean, dry bedding.

Another adverse consequence of late-spring calving is that 80 days later your breeding season tends to fall upon the hottest days of July and August. Heat stress of both cows and bulls is a major reason behind an extended breeding season, which the following year leads to an extended calving season beyond 70 days.

University and extension research has clearly proven heat-stressed cows are more likely to remain open, because they are less likely to ovulate, have irregular estrus cycles, may have poor conception rates, and suffer from a high rate of early embryonic deaths. Similarly, these “dog days” of summer can literary sterilize otherwise fertile bulls for the next couple of months.

Luckily, most episodes of heat stress amongst the beef herds in Western Canada last for only a few weeks during a typical Prairie summer and can be largely regional in scope.

No matter how the weather turns out in the late spring or summer for spring calving and the subsequent breeding seasons, or even how much actual winter-feed costs are saved, the real success story of a late-spring calving season is based upon the total income generated from the amount of saleable pounds of weaned calves sold. †

About the author

Columnist

Peter Vitti is an independent livestock nutritionist and consultant based in Winnipeg. To reach him call 204-254-7497 or by email at [email protected]

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