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Newborn Calf Jeopardy

This high fibre substance links the summer of 2008 with poor doing new born calves in 2009. If you answered "what is poor hay quality", you are probably one of many Ontario beef farmers having a frustrating calving season (and give yourself 100 pts.). What is behind the disturbing number of calves which lack the vigour to get up and find a teat, who are acting like "dummies" and seem to lack the will to survive? In many instances, the problem comes in the form of round bales of hay which have filled the feeders during the winter. But these calves were actually placed in jeopardy due to events which occurred 7 or 8 months previously.

The haying weather of 2008 is something many farmers would like to forget. Lengthy stretches of wet weather kept delaying hay cutting and often interrupted the baling of the crop once it was finally in the swath. When 1st cut and 2nd cut are being baled the same week, you know you are in trouble! The negative effects of delayed harvest and rain on the cut crop combined to produce hay that is both low in nutrients and unappetizing to cows.

Delayed Harvesting

As forage plants mature, the concentrations of precious nutrients decrease and the overall digestibility of the whole plant decreases. Recent research by AAFC scientists shows that for timothy after the late heading stage, for each 1 week delay in harvesting, dry matter digestibility decreases by 7%, and digestibility of neutral detergent fibre (NDF) decreases 10%. At the same time, %NDF content of the forage increases by 5% per week.1 Higher %NDF% means a "bulkier' forage, and is negatively related to the cow's feed intake. We also know that %protein decreases as plants mature and the leaf:stem ratio decreases. And accompanying these changes is a decrease in mineral concentrations in the plant. All of these factors combine to dramatically decrease the nutritional value of forage plants as they grow and mature: the cow will eat less of the poorer feed, amplifying the effect of lower nutrient concentrations. This if reflected in the dramatic decline in net energy content of alfalfa and timothy as they mature illustrated in Fig. 1. And since rain does not slow down the plants' growth, feed quality continues to decline as we sit at the window listening for a weather forecast for "3 or 4 dry days".

Figure 1. Effect of Stage of Maturity on Nutritive Value of Forages2

Text equivalent of graphic

Effect of Rain on Swathed Hay

And now for the really bad news: rain on swathed hay makes the hay quality even worse! Delays in dry down means that the hay plant continues to respire, using up its energy. And nutrients like protein, mineral and sugars are water soluble, and get leached out of the cut hay each time it gets rained on. And it doesn't take much rain to do damage … as little as 1.25 mm of rain will cause significant nutrient loss in hay that is partly cured! For a final insult, raking rained on hay can cause significant leaf loss, further reducing feed value. What's left in this hay? At its worst, it approximates the straw that would normally be used for bedding.

Cow Nutritive Deficit Impacts The Calf

Pregnant beef cows that have kept the fetus for 3 months are physiologically committed to carry it to term. As fetal growth starts to accelerate in mid gestation, the demand for energy, protein, minerals and vitamins ramps up. The cow needs to consume these nutrients in adequate amounts to grow a healthy calf and maintain her own health. If nutrient intake is significantly below requirements, she will deplete her own body resources, including fat, her muscle protein and her stores of minerals and vitamins. As a result, she may lack sufficient muscle tone and endurance to deliver the calf quickly and efficiently. Long deliveries put stress on both the cow and her calf. In severe cases of under nutrition of protein and energy, calves are born weak and "stupid" . They may be suffering from acute Vitamin E/selenium deficiency (White Muscle Disease), leading to extreme muscle weakness. Overall, calves from malnourished cows lack the muscular strength and coordination to get mobile, and lack the mental alertness and drive to bond with the cow and fulfill their instinctive urge to find the udder and suckle vigourously. Without help many of these calves will die. Those that survive will be at risk from infectious disease, as they may not obtain adequate colostrum volume, and these cows will likely produce low quality colostrum which is deficient in immunoglobulins.

Figure 2. Vigourous Calves Consume Adequate Colostrum

Calves born into this whirlpool of negativity may succumb early, or they may struggle through calfhood after suffering setbacks from diarrhea and other diseases. They will likely be smaller at weaning due to lowered maternal milk production and the impact of disease. Cows in this situation will be slow to cycle and breed back, and are at risk of coming up open in the fall.

Paying Down The Nutrient Deficit

While all of this may seem a little overwhelming to accept as being the result of summer rainy spells, there are actions we can take to make things better.

If an alarming number of weak calves are born in a calving season:

• Get your vet out
  • The cause may be due to an infectious disease such as BVD. Swift action is needed to find out if pathogens are the culprit and mount an effective campaign against them
  • Get dead calves necropsied
• Inject newborns with Vitamin E/selenium, and Vitamins A and D
• Discuss with your Vet the idea of injecting the cows with Vitamin E/selenium
• Provide supplemental colostrum (fresh or frozen) or artificial colostrum products to calves which did not strongly suckle within the first 12 hrs, or whose dams who do not appear to be milking well
• During cold or rainy weather, get weak calves dried off and warmed up, then started on the cow or fed supplemental colostrum
• Put the cows on your best forage. If you don't have good quality forage, then feed each cow a few lbs per day of an energy/protein concentrate
• Provide cows with a salt/mineral mix which contains the right levels of calcium and phosphorous, and adequate levels of trace minerals and vitamins

After the calving season

• Ensure cows are gaining weight going into breeding
• Keep them on good quality pasture or supplement with an energy/protein concentrate
• Provide a salt/mineral mix that has the right Ca and P levels to match the feed, and contains adequate levels of selenium and other trace minerals such as zinc, iodine, copper, manganese and cobalt

Fall/Winter

• Get lab analyses done on your stored forages
• Feed a salt/mineral mix to match the calcium and phosphorous in your feed, and which contains adequate levels of all of the trace minerals and vitamins
• Body condition score cows and group them for feeding - thinnest cows get the best forage
• Supplement with energy and protein as needed
• Monitor cows over the winter and make adjustments to the feeding program if necessary

References

1. Pelletier, S., etal. 2008. Delayed Harvest Effects Mineral and NDF Concentrations, and Digestibility of Timothy. Can. J. Anim. Sci. 88: 325 - 329
2. University of Wisconsin. 1994. Nutrition and Feeding Technical Guide

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