The effects of different energy sources in the lactation diet on sow and piglet performance were assessed in association with effects on the metabolic state of the sow around peak lactation. Either maize starch (S) or soya-bean oil (F) was added to a basal diet to provide 0·34 of total digestible energy (DE) intake, such that the experimental diets provided the same daily intakes of DE and crude protein. Twenty-four multiparous sows were allocated between two groups at farrowing, each given one of the two dietary treatments for a lactation period of 28 days. Sow weight and backfat (P2) as well as individual piglet weights were measured on a weekly basis. Litter sizes were standardized to 10 piglets. Milk samples were collected from sows on days 8, 12, 17, 21 and 25 of lactation to measure milk composition and prolactin concentrations. Blood samples were taken via an ear vein catheter from a subsample (7 S, 6 F) of sows on day 14 of lactation; two pre- and seven post-feeding samples were taken at 60-min intervals to measure plasma prolactin, insulin, glycerol, triglyceride, non-esterified fatty acid, urea, b-hydroxybutyrate and glucose concentrations. There was no effect of energy source on sow weight or P2 loss or on subsequent weaning-to-oestrus interval. Sows offered starch weaned more piglets than sows offered soya-bean oil (9·4 v. 8·4, P < 0·05). Litter weight gains were higher for S than F sows in week 3 of lactation (2·2 v. 1·7 kg/day, P < 0·05), irrespective of litter size. Significantly increased plasma urea and b-hydroxybutyrate concentrations and lower post-prandial increases in plasma glucose and insulin concentrations were observed in F sows around peak lactation. Neither milk nor plasma prolactin concentrations were significantly affected by dietary treatments. The metabolic indices indicated that the F diet was more limiting in dietary glucose availability, which was associated with impaired milk yield as indicated by poorer litter performance. In conclusion, this study suggests that starch is superior to fat as an energy source in sow lactation diets, particularly in the later stages of lactation.

Finland's cold loose housing systems (CLH) for dairy cows have been compared to the more traditional warm loose housing systems (WLH) in regard to the incidences of udder and ovarial disorders, ketosis, parturient paresis and metritis. For both systems approximately 10,000 calvings on 210 farms during the years 1996 and 1997 were modelled using survival analysis and two-level logistic regression in an observational cohort study. The results of the different multivariable models, the modelling process, model diagnostics and sample size and confidence limit analysis were combined in an attempt to estimate an unbiased risk ratio. The estimated risk ratios show that there are some differences in the incidence of production diseases between the 2 farming systems. It could be seen from the diagnostics that they were influenced considerably by the modelling process and some 'influential farms'. Even though some disease incidences differed statistically significantly, the observed differences were small so that we concluded that they should not influence the farmers decision making about whether or not to build a CLH in Finland. ASSOCIATIONS BETWEEN DAIRY COW SOMATIC CELL COUNT AND FOUR TYPES OF BEDDING IN FREE STALLS Kirkegaard P, Agger JF, Bjerg B.Department of Animal Science and Animal Health. The Royal Veterinary and Agricultural University, Grønnegårdsvej 8, DK-1870 Frederiksberg C, Denmark.The purpose was to test the hypothesis of no difference in associations between four types of bedding material in free stalls and the cow somatic cell count (SCC) in a study population of primiparous cows in 52 Danish dairy herds. The types of bedding were 1) sand (20-25 cm deep), 2) straw (20 cm deep), 3) channel mattresses (channel bags filled with rubber granulate and a permeable top shield), and 4) two-layer mattresses with foam rubber and a rubber top cover. These bedding types were chosen because they all provided the necessary cow comfort. The herds were randomly selected within each of the four types of bedding systems and represented all regions of Jutland in Denmark. Information on the stable interior and hygiene, cow hygiene, feeding, health management, milking and ventilation were collected at farm visits. Data on milk production and somatic cell count were provided from The Danish Cattle Data Base.

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Relationships between sow nutrition, milk yield, milk composition and piglet performance during lactation have been studied in numerous experiments. However, the subsequent effects of these pre-weaning factors on post-weaning piglet performance are less well studied. Commonly a growth check in piglets in response to weaning is noted, but to date it is unknown why some piglets do better than others in this period. The present experiment explored some of the pre-weaning factors that could explain the variability in piglet post-weaning growth.The performance of piglets from 41 litters was monitored during a lactation period of 26 days. Litter size was standardised to 10 piglets, which were not offered creep food. Piglets were weighed individually on a weekly basis from farrowing to weaning at 26 days. Daily litter milk intake was estimated by a weigh-suckle-weigh technique in 24 litters on 4 occasions at 5 day intervals across lactation. On the day after each of these days, the composition of milk was determined from milk samples obtained by hand milking following oxytocin injection. Litter milk intake and composition of milk were used to calculate the mean daily piglet nutrient intakes during lactation. After weaning some piglets were sacrificed for the analysis of body composition and 310 piglets out of the 41 litters were penned in litter groups in controlled environment flat decks for two weeks to monitor daily group feed intakes and weekly individual growth rates.