WHILE MANY high yielders face a summer with little time outside, the owners of NMR”s highest yielding herd of 2004, averaging 13,061kg, will be making their top performers rely heavily on grazed grass.

High yielding herds which stay indoors must be more prone to disease and stressful conditions in summer, such as dermatitis and mastitis, says Andrew Sanders.

 That”s why the Sandisfarne herd he runs with his wife Sue on the Isle of Man will spend much of the next six months outside at grass.

 “I feel that walking to grazing is very important in getting exercise and cows are much fitter for it.” He believes this is a crucial factor in making cows last longer in the herd.

One of his measures of success on longevity is total lifetime yield. Currently there are 15 cows in the 360-cow herd which have produced 100t plus and 111 which have produced 50t plus. The oldest cow is 16 years old and the aim is 8-10 lactations with a high average daily yield.

“We turn-out in March because there are no frosts on the island. The milking herd is split into highs, lows, heifers and crocks. Lower yielders and heifers walk the longest distance each day – up to 5km,” says Mr Sanders.

It is not exercise that gives cows bad feet, but forcing them along using an ATV will, he adds. “Our cows walk at their own speed, using the carrot approach of concentrate in the parlour and new grazing after milking.”

Although it”s complicated to manage, the Sanders try to send cows in a different direction after each milking, keeping them interested in going out to find fresh grass.

“High yielders walk the middle distance, going furthest in the morning.” Crocks – old or sick cows – and fresh calvers stay near the buildings.

 He says there are usually 10-15 cows in this group. “Any cow which starts to struggle for any reason is put in the crocks group, which is milked twice a day.” The rest of the herd is milked three times a day.

While having four groups at grass may seem complex, he prefers to keep heifers separate, particularly in early lactation. This avoids bullying and gives them a stress-free life, says Mr Sanders.

 “But good quality tracks are a must, as is avoiding muddy conditions.” Before the Sanders arrived it was a beef and sheep unit, so they have invested in tracks to segment the farm – using materials from the farm.

“By October, the soles on cows” feet have become quite thin, so we avoid stony tracks.” And by grazing cows for six months a year, it is rare for feet to become overgrown, adds Mr Sanders.

 During summer cows diets rely heavily on grazed grass, usually with no other forage fed between May and August. But this grass is high in rumen degradeable protein, so parlour compound is reduced to 14% protein. Concentrate use averages 3.6t/cow a year.

 Up to April and from September until housing, cows are buffer fed with whole-crop and round bale silage. Clamp silage is not made because they found chopped round bales in a mixed ration provided the perfect long fibre cows needed. Baled silage also has a lower acid loading allowing high levels of concentrate to be safely fed.

The six-month grazing, six-month housed system is fairly unique to the UK. Only Ireland and possibly Holland also follow this practice, says Mr Sanders. “Elsewhere in the world cows are either housed all year or graze all year. Genetics for those systems will not suit ours.”

He has found that Dutch genetics have performed best under his system on the Isle of Man, where the family moved from Wales in 1997.

 “We are looking for thicker, stockier cows which can cope with all weathers, harsh grazing conditions, walking and cubicles, with as high an index as we can find within that remit.

“But, recently, with high quality bulls from the UK becoming available, we have returned to British tested genetics after a 20-year gap.”

 However, particularly for high index cows, a 365-day calving interval is not a priority. “A high index cow may not see a dose of semen until 200 days into lactation when she is giving more than 50 litres a day.”

 She must be happy with life and on an upward plane of nutrition before she is served.

 Mr Sanders believes this avoids having burnt out cows after three years of progressively losing weight. It also practical because the herd calves all year round.

He admits the herd”s rolling average yield would be higher than its current 12,400 litres if the average lactation were shorter. But vet costs and replacement rates would be higher, too, he adds.

 jessica.buss@rbi.co.uk