Fig 1 Daily nutrition requirements for fresh calvers


Nutrient


Maximum target levels


Dry Matter Intake 19kg CP


16%


M/D DUP


MP – E MCP-E


MCP N/E Starch Sugar NDF


fNDF Calcium


Phosphorus Magnesium Sodium RSV


DCAB


12 MJ/kg DM 900g 102%


1,500g daily intake


115%


16% DM 6% DM 37% DM 26% DM 1.0% DM 0.4% DM 0.3% DM 0.4% DM


40 above min 300mEq/kg DM


Source: Advanced Nutrition


the last two weeks prior to calving you need to think about protein and energy provision as well as calcium balance to drive them forward.


It is advisable to feed an overall 14% CP and energy of about 115MJ ME. If you can also stimulate her into active hormonal calcium mobilisation during this period she will be more energetic at calving and immediately look for food.


Condition is key as a very lean or over


conditioned cow is always harder to get in calf. If she is in energy defi cit and, therefore, hypoglycaemic, then the diet will have a negative impact on insulin and glucose production, which will in turn have a negative impact on follicle growth. The liver will simultaneously release ketones while she is mobilising reserves to make up for the


energy defi cit, which in turn will have a negative effect on the hypothalamus and, therefore, on the pituitary. Again this will have a negative impact on follicle growth.


If there is excess starch in the diet or sugar has been fed in the dry period, then insulin resistance may occur which can predispose to fatty liver. Insulin is critical for reducing hepatic gluconeogenesis,


THE JOURNAL DECEMBER 2014 121


stimulating lipogenesis and consequently removing glucose to tissues and reducing build up in the liver. So what’s going on during a cow’s reproductive cycle to impact on fertility? A plethora of hormones kick in – melatonin, gonad reducing, follicle stimulating and luteinising hormones, oestrogens, progesterone and prostaglandin, however, follicle quality is dependant on how you manage the cow through from the dry period, so once again get this bit right and you’ll be 70% of the way there. However, for these hormones to be released in turn in suffi cient quantity to achieve a functioning reproductive cycle, then each member of the freshly calved herd must be fed a diet which comprises a raft of minimum nutrition requirements – see Fig 1, and taking in the following


1 Sources of degradable nitrogen - grass silage, urea, soya, together with high-energy fodder, for example, maize to improve fertility


2 Suffi cient starch


3 Suffi cient available minerals and vitamins, particularly selenium, vitamin E, zinc, cobalt


4 Adequate NDF from forage to ensure drive rumen function and healthy cows


Other supplements can be used to help fertility and will give you extra benefi ts as long as the basics are right - though they may be expensive and without the benefi ts. For example, Omega3 fi sh oils increase the chance of embryonic implantation and improve embryo quality as well as reducing the delay to ovarian cycling. They work by reducing prostaglandin production and are precursors to progesterone production thereby stimulating the corpus luteum and encouraging more progesterone production.


Following the nutritional guidelines in Fig 1 will help ensure fresh cows have a chance of starting lactation healthily, milking well and getting back in calf, but this will be dependent on condition of each cow coming in from the dry period as well as the management and facilities on farm for these freshly calved cows.


Turn out


The above diet will help ensure optimal dry matter intake and minimise body condition loss while cows are housed, achieving that balance at turn out is more of a challenge. Meeting newly calved cows’ energy requirements to balance the readily available protein is diffi cult, consequently the best solution is for fresh cows to be at least buffer fed if not kept housed until confi rmed pregnant, particularly when they are high yielding. In grazing cows the supply of starch without upsetting rumen function can also be limited and this can have an effect on fertility hormone production and, therefore, impact on the cows’ ability to get back in calf.


PHOTOGRAPY BY JOHN EVENSON


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