JOURNAL OF THE SCIENTIFIC AGRICULTURAL SOCIETY OF FINLAND 239 Maataloustieteellinen Aikakauskirja Vol. 49: 239 -249, 1977 Grass intake and behaviour of young calves fed on pasture or zero-grazing Paavo Tiihonen1) Department of Animal Husbandry, Agricultural Research Centre, 001200 Vantaa 30 Esko Poutiainen Department of Animal Husbandry, University of Helsinki, 00710 Helsinki 71 Abstract Comparisons were made between two groups of four Ayrshire calves, one group feeding on pasture and the other fed indoors on cut grass as the only food between 8— 18 weeks of age. For determination of pasture grass intake of clipping method was compared with the indicator technique, chromium oxide being used as an indicator. Studies on behaviour were made to clarify the development of the ruminating function of the calves as well as the effect of cut and pasture grass plus a concentrate supplement on their behaviour. The digestibility of organic matter of pasture grass was I—4 %-units higher than that of cut grass. Intake of grass indoors was approximately 1940 g DM per animal per day. With the clipping method the average intake of pasture grass was 1355 g DM per animal per day and with the indicator technique 2061 g. The latter value seemed to be nearer the correct one, if a conlcusion is to be drawn from the live weight gain of the calves. Time used for intake of grass increased rapidly once the liquid feedingperiod was ended, that is during the whole experimental time up to eight of the 14.5 hours of the observation interval. Calves at the age of 26—37 days ruminated for approximately 116 min in eight hours. Supplementation of concentrates considerably decreased the time spent eating and increased the time spent ruminating by a small amount. Introduction As soon as a calf’s rumen functions have developed, high quality animal protein required by a non-ruminant calf can be replaced withvegetable protein without any detrimental effect on the live weight gain of the animal. Diet has an important effect on the development of a calf’s alimentary tract. If the allowance of liquid milk is restricted and hay as well as concentrate is offered from the first week of the calf’s life, its rumen functions become fully developed by 6—B weeks of age (Roy 1970 b). x) Present address: Ypäjän maatalousoppilaitos, 32100, Finland https://www.c-info.fi/en/info/?token=-zapqr3o3K9r2FSm.xRDlo9qWbk1uodLfMejWbw.tzf5Q-weSeEYulFU-nQRaB-wqXNXRm1Z7JmT8qg0SHoN9aTx7uKTxGG47_PediaFLqU6d2-gfKAQ0fLSqvj6jCBsglK1s5Yns7-e8LrxZozFl2DEAB1tQP5z1PI0m7IlwhXEWcDotfacPAOn7fUzCuaUqOnbOOBiiUT3J5MBDgsxwlegEy9nJX59hTEa 240 If the ruminant calf is raised mainly on pasture and corn concentrate the energy and protein content of grass at the pasture stage of growth or at the stage of growth prior to harvesting for silage meets it’s nutritional requirement (Wilkinson and Tayler 1972, Poutiainen and Huilaja 1972). However, grazing behaviour and the physiological capacity of the calf’s alimentary tract, which affects the digestibility and utilization of the feed, could limit growth. Young calves fed on good pasture and limited quan- tities of diluted milk concentrate have progressed as well as calves fed conven- tionally indoors (Chambers 1961, Meadowcroft and Turner 1971). In addition to grass, concentrates are recommended for the Ist 5—6 weeks of age (Roy 1970 a). Experiments with older beef cattle have given comparable results between cut grass and grazed pasture (Stewart and McCullough 1972,Turner 1972). It is due to herbage selection live weight gain per kilogram of dry matter has often been better with grazing than with cut grass feeding (Meyer et al. 1956). Contradictory results obtained with young calves (Alder and Copper 1967) are thought to be due to young animals being very critical in diet selection (Hodgson and Rodrigues 1971). Live weight gain per hectare has been cal- culated to be 20 to 40 percent higher for calves fed on cut grass than for those raised on pasture. Grasses selectively grazed differ in their composition and digestibility value from those harvested at the same stage of growth especially during mid and late summer (Hardison et al. 1954) causing diffi- culties in the determination of the grazing intake. The clipping method, earlier in general use, does not give exact results so, at present, the indicator technique and eosophageal fistula methods are preferred (Hodgson 1968). The experiment reported here is a part of an extensive series of grazing and silage feeding experiments with cattle in which a special emphasis is placed on the use of grass as a protein source. The purpose of this work was firstly to investigate the ability of a young calf to use grass as its only nutrient other being fed a strict diet of diluted milk concentrate from birth to eight weeks of age and, secondly, to compare grazing with cut grass feeding. When determining the grass intake of grazing calves the clipping method was compared with the indicator technique. Observations of the behaviour of the calves were made in order that the development of ruminant functions and indoor and outdoor behaviour patterns could be followed. Materials and methods Animals and management Eight male Ayrshire calves were divided into two groups of four. One group I a (of average age 58.0 days and live weight 61.6 kg) was grazed on pasture and the second group I b (of average age 57.7 days and live weight 66.0 kg) was fed cut grass. In a parallel experiment two groups of 16 female Ayrshire calves of same age as male calves were treated as follows. II a) Grazed on pasture and fed 1.5 kg per calf per day of concentrated supplementary feed. II b) Fed cut grass and 3.0 kg per calf per day of concentrated supplementary feed. 241 Before the experiment begun the calves received 4 litres of diluted milk concentrate, a maximum of 0.5 kg of hay and a maximum of 1.5 kg of con- centrate (40 % barley, 40 % oats and 20 % protein concentrates) per animal per day. Water and a mineral vitamin mixture were freely available. Fresh herbage was first given to the individually tethered and fed calves at 6 weeks of age. The groups I a and II a were turned out to graze on 30 June and the other two groups (I b and II b) were fed cut grass indoors. A block grazing rotation was used with a complete rotation taking 5 days. Topping was performed on the day calves were moved from one plot to another one half of each block being cut daily for the indoor fed group. The grass, water and mineral mixture were offered ad lib. to both groups. Composition of the grass The sward used was in it’s fifth year and predominantly cocksfoot, in which there was plenty of weed. The cut grass and pasture grass were quite similar i their average chemical composition (Table 1). Table 1. The average botanical and chemical composition of the herbage samples. Botanical composition Chemical composition Plant species % cut grass pasture grass % DM % DM Cocksfoot 66 Ash 8.7 9.2 Timothy 7 Crude protein 19.2 18.9 Other cultivated species 5 Crude fat 4.3 4.1 Weed 22 Crude fibre 23.8; 23.1 N-free extract 44.1 44.7 Determination of the intake and digestibility of herbage Digestibility The digestibility of cut grass was determined by the total collection method in two periods of ten days, between 19.—28. July and 18.—27. August. Preparation and chemical analysis of the feeds and faeces were made ac- cording to conventional methods. The digestibility coefficients were calculated according to the SUKO programme (Anon. 1971). The average age of the calves was 76 days at the beginning of the first collection period and 106 days at the beginning of the second. The digestibility of pasture grass was determined by using the nitrogen content of the faeces as an indicator and applying an appropriate correction method (Anon. 1961). For the experiment the generally accepted equation y = 6.11 X + 56.0 (Greenhalg and Runchie 1962), where y = digestibility of the organic matter in the herbage and x = nitrogen content of the faeces organic matter expressed as a percentage was used. For cut grass the in vivo digestibility of the organic matter (y) received by various calves arid the mean values of the nitrogen content of the faeces (x) were placed in the above equation and new values were calculated as standards in each collection period. Determination of the herbage intake Intake of grass by the animals kept on pasture was determined by using, as an indicator, paper impregnated with Cr203 . A dose of three grams of paper was given to each calf twice a day at 8.00 hr and at 15.00 hr together with five grams of plastic granules of different colours for identifying the faeces. A spoonful of faecal samples was collected from each pale at 8.15 hr and 21.00 hr. The daily faecal samples from each calf were preserved individually, by deep freezing. The chromium oxide content of the faecal organic matter was measured chemically. Calculation of the organic matter in the faeces and the organic matter intake was made according to the following formulae using the digestibility index method, and correcting according to the faecal index method deter- mined for pasture feeding (Anon. 1961). g Cr2O a fed/day Organic matter in faeces in kg/day g Cr 2 O a/kg faecal organic matter kg faecal organic matter/dayOrganic matter eaten in kg/day = 100 x 100 digestibility % of organic matter Behaviour observations Behaviour observations were made on the 8 male calves (groups I a and I b) and 8 of the female of a similar age (groups II a and II b). The same observations were done on both sexes as separate but corresponding groups (Table 2). Table 2. The observation periods and feedingregimes. The male calves were on pure grass diets and the female calves had 1.5kg concentrate/head/day. Age (days) Period Date Animals at the beginning Diet Time observed of observation 1 25.-26.5. 4(J +4o 17.1 Diluted milk concen- trate feed 2 successive days, during daylight hours (ä 8 hrs) 2 7. 8.6. 4(J +4O 30.1 Diluted milk concen- trate feed 2 successive days, during daylight hours (ä 8 hrs) 3 28. —3O. 6. +4o 51.1 Drv feeding 48 hrs continuously + 4a 31.7. 2.8. A$ 4- 4o 86.8 Fed cut grass indoors 48 » + 4b 2.-4.8. 4ö*+4o 88.0 Grazed on pasture 2 successive days, during daylight hours (ä 8 hrs) 5a 29. —3l. 8. 4