Effect of precalving and postcalving dietary energy level on performance and blood metabolite concentrations of dairy cows throughout lactation.

The effects of the level of energy intake (high E and low E) offered before and after calving on body condition score at calving, production performance, and energy status in the first 250 d of lactation were evaluated in a 2 × 2 factorial design experiment involving 80 Holstein-Friesian dairy animals (40 primiparous and 40 multiparous). From d 80 until d 21 precalving, primiparous animals were offered either high or low pasture allowances. Thereafter, these animals were housed and had ad libitum access to a high energy density diet (high E) or restricted access [6 kg of dry matter (DM) per d] to a low energy density diet (low E), respectively, until calving. From d 100 until d 42 precalving, multiparous animals were offered either ad libitum or restricted (10 kg of DM/d) access to a late lactation diet, and thereafter, had ad libitum access to a high E diet or restricted access (7 kg of DM complete diet/d) to a low E diet, respectively, until calving. The forage to concentrate (F:C) ratios (DM basis) of these high E and low E diets [d 42 (d 21 in primiparous animals) until calving] were 64:36 and 83:17, respectively. Cows offered high E and low E precalving diets were allocated to either a high E or low E postcalving diet [F:C ratio (DM basis) of 30:70 and 70:30, respectively] and remained on these diets until d 250 of lactation. Multiparous animals offered a high E diet precalving had a significantly higher body condition score at calving than those offered the low E diet precalving. This effect was not evident in primiparous animals. Precalving diet had no significant effect on plasma nonesterified fatty acid concentrations during the last 3 wk precalving in primi- or multiparous animals. Primiparous animals offered a high E diet precalving had significantly higher postcalving plasma concentrations of nonesterified fatty acid, suggesting greater mobilization of body reserves. Primi- and multiparous animals offered a high E diet postcalving had a significantly higher dry matter intake, milk yield, and energy status postcalving compared with animals offered a low E diet postcalving. Milk yields of primiparous animals offered high E and low E diets postcalving were 29.7 and 24.8 kg/d, respectively, and milk yield of multiparous animals offered high E and low E diets postcalving were 33.5 and 28.2 kg/d, respectively. It is concluded that altering body condition score during the dry period is difficult but that specific dietary regimens applied precalving can have a significant influence on postcalving production and energy-related parameters.

Effect of offering dairy cows diets differing in phosphorus concentration over four successive lactations: 1. Food intake, milk production, tissue changes and blood metabolites.

The loss of phosphates from dairy farms contributes to the eutrophication of waterways. Whilst reducing the phosphorus (P) content of dairy cow diets has the potential to help reduce phosphate losses, diets containing inadequate dietary P may have a negative effect on cow health and performance. To address this issue, 100 winter-calving Holstein-Friesian dairy cows were offered diets containing either 'high' or 'low' levels of dietary P. The experiment was conducted over a 4-year period, with 80 primiparous cows commencing the study in year 1, while a further 20 primiparous cows commenced the study in year 2. Rations offered during the winter comprised grass silage, maize silage (70 : 30 dry matter (DM) basis, approximately) and concentrates (10.0 to 12.0 kg/cow per day). During the summer periods in years 1 and 2, half of the cows grazed both day and night, while the remaining cows grazed by day, and were housed by night and offered grass silage. During years 3 and 4, all cows grazed both day and night during the summer period. Concentrate feed levels during the summer periods were 3.0 to 4.0 kg/cow per day. Different dietary P levels were achieved by offering concentrates containing either high or low P levels during the winter period (approximately 7.0 or 4.4 g P/kg DM respectively), and during the summer period (approximately 6.8 or 3.6 g P/kg DM, respectively). Total ration P levels averaged 4.9 and 3.6 g P/kg DM for the 'high' and 'low' P winter diets respectively, and 4.2 and 3.6 g P/kg DM for the 'high' and 'low' P summer diets respectively. A total of 95, 70, 50 and 22 cows completed each of lactations 1 to 4 respectively. Dietary P level had no significant effect on food intake, milk output or milk composition (P > 0.05). Plasma P concentrations were significantly lower with cows offered the 'low' P diet in each of lactations 1 to 4 (P < 0.05). In each of lactations 3 and 4, cows offered the 'low' P diet tended to have lower condition scores and live weights than those offered the 'high' P diet. The results of this experiment highlight that the P content of dairy cow diets can be substantially reduced with no detrimental effect on dairy cow performance.

Effect of offering dairy cows diets differing in phosphorus concentration over four successive lactations: 2. Health, fertility, bone phosphorus reserves and nutrient utilisation.

This experiment examined the long-term effects of offering diets containing low levels of dietary phosphorus (P) on dairy cow health, fertility and bone composition, and the effect of dietary P level on nutrient utilisation. One hundred winter-calving Holstein-Friesian dairy cows were offered diets containing either 'high' or 'low' levels of dietary P over a 4-year period. Rations offered during the winter included grass silage, maize silage (70 : 30 dry matter (DM) basis, approximately) and concentrates (10.0 to 12.0 kg/cow per day). During the summer periods in years 1 and 2, half of the cows grazed both day and night, while the remaining cows grazed by day, and were housed by night and offered grass silage. During years 3 and 4, all cows grazed both day and night during the summer period. Concentrate feed levels during the summer periods were 3.0 to 4.0 kg/cow per day. Different dietary P levels were achieved by offering concentrates containing either high or low P levels during the winter period (approximately 7.0 or 4.4 g P/kg DM, respectively) and during the summer period (approximately 6.8 or 3.6 g P/kg DM, respectively). Total ration P levels averaged 4.9 and 3.6 g P/kg DM for the high and low P winter diets, respectively, and 4.2 and 3.6 g P/kg DM for the high and low P summer diets, respectively. A total of 95, 70, 50 and 22 cows completed each of lactations from 1 to 4, respectively. Neither the incidence of lameness or mastitis, or milk somatic cell count, were affected by dietary P level (P > 0.05), while none of the fertility parameters recorded in any of lactations from 1 to 4 was affected by the dietary P level (P > 0.05). Dietary P level had no effect on the specific gravity, ash or calcium content of rib cortical bone cores (n = 78 cows), while the P content of cortical bone (g/kg fresh, g/kg DM and mg/ml fresh bone) was lower with cows offered low P diets (P < 0.05). Dietary P level had no significant effect on the digestibility of either the DM, nitrogen, energy or acid detergent fibre fraction of the diet (P > 0.05), while faecal P excretions were reduced by a mean of 27 g/cow per day with cows offered the low P diets during the winter period. The results of this study indicate that dietary P levels can be reduced to proportionately 0.8 (approximately) of current UK feeding standards (Agricultural and Food Research Council, 1991), with no detrimental effect on dairy cow health or fertility, while having only minor effects on bone composition.

Effects of plane of nutrition of ewes in early and mid-pregnancy on performance of the offspring: female reproduction and male carcass characteristics.

This study investigated the effects of different planes of nutrition in early pregnancy (EP) and mid-pregnancy (MP) of crossbred ewes on carcass characteristics of male offspring and reproductive performance of female offspring. During EP (d 1 to 39 after synchronized mating) ewes were allocated 60% (low, L-EP), 100% (medium, M-EP), or 200% (high, H-EP) of their energy requirements for maintenance. Between d 40 and 90 (MP), ewes were then allocated 80% (M-MP) or 140% (H-MP) of their maintenance energy requirement. After d 90, all ewes were fed to fully meet energy requirements for late pregnancy. Male offspring (n = 83) were reared on a grass-based system and slaughtered at 42, 46, or 50 kg of BW. Female offspring (n = 60) were reared on a grass-based system, mated at 8 mo, and performance recorded until weaning of their first lamb crop. Concentrations of leptin, an adiposity indicator, in female offspring varied with the plane of maternal nutrition in early pregnancy. The L-EP offspring had greater leptin concentrations than H-EP offspring (P = 0.04), with M-EP offspring showing intermediate concentrations. Reproductive performance of female offspring was not affected by maternal plane of nutrition (P > or = 0.16). Female H-EP offspring gave birth to heavier lambs (generation 2 offspring) than M-EP (P = 0.006) with L-EP offspring intermediate. Male offspring of L-EP dams showed a trend toward poorer carcass conformation (P = 0.06) and increased fat classification (P = 0.07), consistent with increased fat depths over the loin (P = 0.02). There was a significant interaction between plane of nutrition in early pregnancy and mid-pregnancy for female offspring BW at 2 mo postmating and 16 wk postlambing (P < or = 0.04), and for male offspring perinephric and retroperitoneal fat and tissue depth (P < or = 0.02). For dams offered diet L-EP during early pregnancy, diet H-MP gave heavier offspring with more perinephric and retroperitoneal fat. In contrast, for dams offered diet H-EP during EP, diet M-MP gave offspring that were heavier or fatter or both. Maintenance level of nutrition in EP followed by M-MP or H-MP treatments resulted in offspring intermediate in fatness and BW. The data indicate that adaptations in EP and MP to compensate for nutritional deprivation or nutritional excess can alter the BW, adiposity, conformation, and leptin concentrations of offspring. Such changes have potential to alter health and lifetime productive performance.

Effects of breed and production system on lameness parameters in dairy cattle.

The aim of the present study was to assess the effects of Holstein-Friesian (HF) and Norwegian (N) dairy cattle genotypes on lameness parameters in dairy cattle within different production systems over the first 2 lactations. Following calving, HF (n = 39) and N (n = 45) heifers were allocated to 1 of 3 systems of production (high level of concentrate, low level of concentrate, and grass-based). High- and low-concentrate animals were continuously housed indoors on a rotational system so that they spent similar amounts of time on slatted and solid concrete floors. Animals on the grass treatment grazed from spring to autumn in both years of the study, so that most animals on this treatment grazed from around peak to late lactation. Claw health was recorded in both hind claws of each animal at 4 observation periods during each lactation as follows: 1) -8 to 70 d postcalving, 2) 71 to 150 d postcalving, 3) 151 to 225 d postcalving, and 4) 226 to 364 d postcalving. Sole lesions, heel erosion, axial wall deviation, sole length of the right lateral hind claw (claw length), right heel width, and right lateral hind heel height were recorded as well as the presence of digital dermatitis. The N cows had lower (better) white line and total lesion scores than HF cows. Cows on the high- and low-concentrate treatments had better sole and total lesion scores than cows on the grass treatment. The HF cows had better locomotion scores than N cows. Breed and production system differences were observed with respect to claw conformation, including claw length, heel width, and heel height. Digital dermatitis was associated with worse sole lesion scores and interacted with production system to influence white line lesion scores and maximum heel erosion scores. This study shows that genetic, environmental, and infectious factors are associated with hoof pathologies in dairy cows.

Effect of supplementation with barium selenate on the fertility, prolificacy and lambing performance of hill sheep.

Six weeks before mating, the ewes on six hill farms were randomly assigned to receive either a subcutaneous injection of a long-acting supplement containing 50 mg/ml selenium as barium selenate, or no injected selenium. Before the treatment, the mean activity of glutathione peroxidase (GSHPx) in the ewes on the six farms ranged from 166 to 592 U/g haemoglobin (Hb) and their plasma selenium concentrations ranged from 0.60 to 1.61 micromol/l. Treated ewes had higher plasma selenium concentrations and higher GSHPx activities than control ewes during the study. Conception rates were higher in the treated ewes than in the control ewes. At six weeks, the lambs born to the treated ewes had higher plasma selenium and GSHPx levels than the controls. The treated ewes reared 9 per cent more lambs than the control ewes. The treated ewes had lower abortion rates, and higher liveweights and body condition scores than the controls. There were weak but positive associations between the plasma selenium and GSHPx levels of the ewes and their reproductive performance.

Effect of plane of nutrition of 1- and 2-year-old ewes in early and mid-pregnancy on ewe reproduction and offspring performance up to weaning.

The objective of the present study was to determine the effect of plane of nutrition in early pregnancy (EP) and mid-pregnancy (MP), on the productive performance of 1- and 2-year-old ewes and their offspring. Over 2 successive years, between days 0 and 39 after synchronized mating (EP), 1- (n = 117) and 2- (n = 52) year-old ewes were allowed 60% (low, L-EP), 100% (medium, M-EP) or 200% (high, H-EP) of requirements for maintenance (M). Between days 40 and 90 (MP), 1-year-old ewes were allowed 140% (M-MP) or 200% (H-MP), while 2-year-old ewes were allowed 80% (M-MP) or 140% (H-MP) of their M requirement. After day 90, all ewes were fed to meet requirements for late pregnancy. Increasing the plane of nutrition between days 0 and 39 resulted in increases in live weight (LW) (P < 0.001) and body condition score (BCS) (P < 0.001) during the EP period (H-EP > M-EP > L-EP), differences that in 1-year-old ewes were sustained to lambing (P < 0.05). On day 42 of gestation H-EP ewes had lower plasma progesterone concentrations than L-EP or M-EP ewes in 1- (P < 0.01) and 2- (P < 0.001) year olds. This was concomitant with diet H-EP tending to reduce the number of lambs born per ewe in both age groups (P = 0.06 and 0.07, respectively). Foetuses from 1-year-old L-EP ewes had smaller cranial (P < 0.01) and abdominal (P < 0.05) diameters at day 53 of gestation, with H-EP lambs tending to be heaviest at birth (P = 0.07). Similar findings were recorded for 2-year-old ewes. One-year-old ewes offered diet L-EP presented negative maternal behaviours more frequently (P < 0.05), while the incidence of lamb mortality at 6 weeks tended to be greater for L-EP lambs (P = 0.07). In MP, 1-year-old ewes offered diet M-MP were associated with foetuses with bigger abdominal diameters at day 78 (P < 0.05). However, there were no differences in lamb weight or size at term (P > 0.05). These ewes exhibited more positive maternal behaviours (e.g. increased grooming frequency and duration; P < 0.05) than ewes offered diet H-MP, and their offspring were more successful in suckling (P < 0.05). Results suggest that in young ewes, a temporary nutrient restriction in EP resulted in increased prolificacy. However, ewes and their offspring were lighter at birth and ewe maternal behaviour was poorer, resulting in increased lamb mortality. In MP, a medium plane of nutrition offered to 1-year-old ewes led to improved maternal and offspring behaviour.

Nutritional status of adult ewes during early and mid-pregnancy. 1. Effects of plane of nutrition on ewe reproduction and offspring performance to weaning.

The objective of this study was to determine the effects of plane of nutrition during early and mid-pregnancy on the performance of mature ewes and their offspring. From day 0 to day 39 post mating (early pregnancy, EP), 82 multiparous ewes were fed to provide either 60% (low, L), 100% (medium, M) or 200% (high, H) of predicted metabolisable energy (ME) requirements for maintenance, following a synchronised mating. From day 40 to day 90 (mid-pregnancy, MP), ewes were provided with either 80% (M) or 140% (H) of ME requirements. After 90 days of gestation, all ewes were fed to meet requirements for late pregnancy. During EP, mean live weight (LW) and body condition score (BCS) change of ewes were -6.3, -0.8 and +6.0 kg and -0.02, +0.10 and +0.22 units in the L-, M- and H-EP treatments, respectively. During MP, mean LW and BCS change were -0.8 and +4.9 kg and -0.09 and +0.09 units in the M- and H-MP treatments, respectively (P < 0.001). Treatments had no effect (P > 0.05) on conception rate, although there tended to be an inverse relationship (P = 0.085) between plane of nutrition in EP and plasma progesterone concentrations at day 42 of gestation. EP nutrition influenced foetal development with lambs from ewes offered diet L-EP being smaller (P < 0.01) at day 56 than M- or H-EP lambs. However, at parturition L-EP lambs were heavier (P < 0.05) and tended to have higher (P = 0.056) immunoglobulin status 24 h after birth. Mortality rates at weaning were reduced (P < 0.05) for lambs born from ewes offered diet L-EP compared with M- or H-EP lambs. Diet M during mid-pregnancy resulted in larger (P < 0.05) foetuses at day 80 of gestation. At parturition, these lambs had longer head and crown-rump lengths than H-MP lambs (P < 0.05). Lambs born to ewes offered diet M-MP tended to progress faster to attempting to suckle than H-MP lambs (P = 0.089). There was an interaction between plane of nutrition in early and mid-pregnancy, whereby the highest number of lambs weaned was a result of diet L-EP followed by diet M-MP. These results indicate that in adult ewes, temporary nutrient restriction during early pregnancy results in better lamb survival; and mild nutrient restriction in mid-pregnancy tends to improve neonatal behaviour and results in lambs with longer skeletal size.

Nutritional status of adult ewes during early and mid-pregnancy. 2. Effects of supplementation with selenised yeast on ewe reproduction and offspring performance to weaning.

The objective of this study was to determine the effects of selenium (Se) supplementation of mature ewes in the period from day -14 to day 90 post mating on Se status, productivity and viability of ewes and their offspring. Multiparous crossbred ewes (n = 82) were randomly assigned to receive a standard dried grass-based diet (control) or dried grass diet supplemented with 1 g of selenised yeast (Selplex®), providing 0.5 mg Se per ewe per day. After day 90 post mating, all ewes were offered grass-based diets supplemented with a standard multivitamin and mineral mix, up to lambing. Ewes that were fed additional Se had increased (P < 0.001) activity of glutathione peroxidase enzyme (GPx) and increased plasma Se concentrations throughout the treatment period. At lambing, GPx activity of supplemented ewes was higher (P < 0.001) than that of controls. Twenty-four hours after birth, lambs of ewes given Se had higher (P < 0.001) concentration of Se in plasma, greater (P < 0.001) activity of GPx and better (P < 0.01) immune status. Lambs of ewes that received supplementation showed a faster progression to stand than control lambs (P < 0.05), independent of maternal behaviour which was not affected. Supplementation reduced perinatal lamb mortality (0.04 v. 0.17; P < 0.05). However, overall mortality from birth to weaning was unaffected (P > 0.05). Supplemented ewes weaned lambs on average 2 kg heavier than control ewes, due to the higher (P < 0.05) growth rates achieved by their offspring. In conclusion, for ewes with a marginal Se status, an organic source of Se supplemented throughout pregnancy, compared with supplementation only in the last trimester, positively affected measures of lamb viability and survival.

Associations between genetic merit for milk production and animal parameters and the fertility performance of dairy cows.

Relationships between genetic merit for milk production and animal parameters and various parameters of reproductive performance were examined using multilevel binary response analysis in a study of 19 dairy herds for three successive years, representing approximately 2500 cows per year. The proportion of cows intended for rebreeding that were back in-calf again within 100 days of calving (ICR-100) and the proportion of cows that reappeared again with 365 (RR-365) and 400 days (RR-400) of a previous calving were considered in addition to the traditional measures of reproductive performance. Each 100-kg increase in genetic merit for milk yield was associated with an increased interval to first service (IFS) and calving index (CI) of 1.4 ( P < 0.001) and 1.8 days ( P < 0.001), respectively, a 0.5% increase ( P < 0.05) in calving rate to first insemination (CR-1) and 0.8% increase in RR-400. Each £10 increase in £PIN (the economically weighted yield selection index used in the UK that takes account of butterfat and protein yields) was associated with an increased IFS and CI of 1.5 ( P < 0.001) and 3.0 days ( P < 0.001), respectively. Cows with increased genetic merit for milk yield and £PIN were more likely to re-calve (RR-overall; P < 0.001). Each 1000-kg increase in 305-day milk yield was associated with an increased IFS and CI of 3.2 ( P < 0.001) and 7.8 days ( P < 0.001), respectively, and a 13.6 ( P < 0.001), 22.4 ( P < 0.001), 19.9 ( P < 0.001) and 19.0% ( P < 0.001) decrease in CR-1, ICR-100, RR-365 and RR-400, respectively. A 10-kg increase in maximum yield was associated with a 6.6-day increase in CI ( P < 0.001) and a 14.9 ( P < 0.001), 18.3 ( P < 0.001), 9.6 ( P < 0.05) and 14.2% ( P < 0.001) decrease in CR-1, ICR-100, RR-365 and RR-400, respectively. Fertility performance was also associated with season of calving, lactation number and dystocia score. Level of production had a larger effect on fertility performance than genetic merit for milk production suggesting that infertility at an individual cow level is more likely to be associated with increased production and an inability to meet the nutritional requirements of the cow.

Hypomagnesaemia and new data on vitreous humour magnesium concentration as a post-mortem marker in ruminants.

Magnesium deficit has been associated with many sub-clinical and clinical conditions in humans and animals. The incidence of hypomagnesaemia is high in lactating cows grazing spring pastures, occasionally resulting in the often fatal condition known as grass tetany. While plasma magnesium concentrations can be used to assess magnesium status in the live animal, post-mortem diagnosis of clinical grass tetany is difficult. Recent studies have investigated the potential of eye fluid magnesium concentration as a post-mortem marker of hypomagnesaemic tetany. In tetany induction studies carried out in adult ewes and lactating cows significant relationships were found to exist between the concentrations of magnesium in either cerebrospinal fluid or plasma and either aqueous or vitreous humour. In freshly dead animals aqueous humour magnesium concentrations of < 0.33 mmol/L in adult sheep and < 0.25 mmol/L in adult cattle were associated with severe hypomagnesaemia and tetany. However, aqueous humour was found to be unstable post-mortem. Vitreous humour was considerably more stable and a vitreous humour magnesium concentration in adult sheep of < 0.65 mmol/L for up to 24 hours post-mortem or < 0.55 mmol/L in adult cows for up to 48 hours was associated with severe hypomagnesaemia and tetany. Provided clear-fluid samples are taken from appropriate animals and processed correctly in the laboratory, the concentration of magnesium in vitreous humour is a useful and practical marker in the post-mortem diagnosis of hypomagnesaemic tetany in ruminants.

Childhood injuries due to falls from apartment balconies and windows.

BACKGROUND: Falls from balconies and windows are an important cause of childhood injury. This study investigated the circumstances around such falls and attempted to identify possible measures for their prevention. POPULATION: Children <15 years living in Dallas County, Texas. METHODS: Each child treated because of a fall from a building in 1997-99 had information about the injury collected, and a parent was contacted to obtain further information. For apartment related falls, an attempt was made to visit the apartment to measure windows and balcony rails. RESULTS: Ninety eight children were injured in falls from buildings during the three year period; 39 (40%) were admitted to hospital. Seventy five of the falls (77%) involved apartments, and most occurred around noon or evening meal times. Among apartment falls, 39 (52%) fell from windows, 34 (45%) from balconies, and two (3%) from unknown sites. For more than two thirds of balcony related falls, the child fell from between the balcony rails, all of which were spaced more than 4 inches (10 cm) apart. On-site measurement showed the rails were an average of 7.5 inches (19 cm) apart; all of these apartments were built before 1984. For more than two thirds of window related falls, the window was situated within 2 feet (61 cm) of the floor. CONCLUSIONS: Two factors are important in falls from apartment windows and balconies: balcony rails more than 4 inches (10 cm) apart, and windows positioned low to the floor. Current building codes do not apply to older apartments, where most of these falls occurred. Nevertheless, these factors may be amenable to environmental modifications that may prevent most of these falls.

Fertility of dairy cows in Northern Ireland.

A comprehensive database was established on the milk production and reproductive performance of dairy cows in 19 selected herds in Northern Ireland, varying in size, management system and genetic merit. Data were obtained for 2471 cows, 1775 of which calved in a second year, and 693 were culled from the herd for specific reasons. The estimated mean rate of heat detection (assessed by the interheat interval during the main breeding season) in all the herds was 71 per cent, with a range from 53 to 92 per cent The average conception rate to first insemination was 37.1 per cent (range 21 to 66 per cent). The average calving interval for the retained cows was 407.2 days (range 359 to 448 days). Twenty-eight per cent of the cows that calved were culled, with infertility being the largest single reason (26.8 per cent of the cows culled). There were major differences in reproductive performance between the herds, but heat detection rate, conception rate and calving interval did not appear to be affeded by a herd's genetic merit. The herds with shorter calving intervals were characterised by better heat detection efficiency (83 v 61 per cent, P<0.01), a shorter interval from calving to first insemination (74 v 97 days; P<0.05), a higher conception rate to first insemination (45 v 34 per cent, P>0.10) and a lower removal rate (23 v 37 per cent, P<0.01). Furthermore, the cows in these herds had lower body condition scores (BCS) in the dry period (3.0 v 3.3; P<0.05) but lost less body condition in early lactation (0.3 v 0.6 BCS units, P<0.05). These results show that dairy herd fertility in Northern Ireland is generally low and similar to that previously reported for England and the USA, but that in some herds changes in herd management practices improved the cows' fertility.

Biochemical changes induced by hypomagnesaemia in lactating cows and ewes.

Severe hypomagnesaemia was induced in lactating cows and lactating sheep by feeding them magnesium-deficient diets for 17 and 14 days, respectively. Hypomagnesaemia in cows was associated with abnormally high rates of change in the numbers of leucocytes, neutrophils, monocytes and platelets. There were increases in the concentration of iron in the liver of the hypomagnesaemic ewes and in the heart of the hypomagnesaemic cows, which were not associated with a haemolytic process. The percentage of some of the peroxidisable fatty acids was lower in the heart tissue of hypomagnesaemic cows, but the reduction was not associated with significant lipid peroxidation.

Deaths and injuries from house fires.

BACKGROUND: We sought to define the factors associated with house fires and related injuries by analyzing the data from population-based surveillance. METHODS: For 1991 through 1997, we linked the following data for Dallas: records from the fire department of all house fires (excluding fires in apartments and mobile homes), records of patients transported by ambulance, hospital admissions, and reports from the medical examiner of fatal injuries. RESULTS: There were 223 injuries (91 fatal and 132 nonfatal) from 7190 house fires, for a rate of 5.2 injured persons per 100,000 population per year. Rates of injury related to house fires were highest among blacks (relative risk, 2.8; 95 percent confidence interval, 2.1 to 3.6) and in people 65 years of age or older (relative risk, 2.6; 95 percent confidence interval, 1.9 to 3.5). Census tracts with low median incomes had the highest rates of injury related to house fires (relative risk as compared with census tracts with high median incomes, 8.1; 95 percent confidence interval, 2.5 to 32.0). The rate of injuries was higher for fires that began in bedrooms or living areas (relative risk, 3.7); that were started by heating equipment, smoking, or children playing with fire (relative risk, 2.6); or that occurred in houses built before 1980 (relative risk, 6.6). Injuries occurred more often in houses without functioning smoke detectors (relative risk, 1.5; 95 percent confidence interval, 1.0 to 2.4). The prevalence of functioning smoke detectors was lowest in houses in the census tracts with the lowest median incomes (P<0.001). CONCLUSIONS: Rates of injuries related to house fires are highest in elderly, minority, and low-income populations and in houses without functioning smoke detectors. Efforts to prevent injuries and deaths from house fires should target these populations.

Effect of concentrate feed level in late gestation on subsequent milk yield, milk composition, and fertility of dairy cows.

The effects of level of concentrate feeding in late gestation on feed intake, milk yield, milk composition, and fertility in the subsequent lactation were evaluated in a randomized block design experiment involving 60 cows. Grass silage was offered ad libitum for the last 28 d of gestation either as the sole diet (OC) or supplemented with 5 kg/d of concentrates (5C). Following calving, the cows were offered the same grass silages supplemented with 7 kg/d of concentrates. For treatments OC and 5C, total dry matter intakes were 9.28 and 11.03 kg/d of dry matter, respectively, during the last 4 wk of gestation. During wk 1 to 12 of the subsequent lactation, treatment 5C increased milk fat concentration but did not alter feed intake, milk yield, or protein concentration relative to treatment OC. Treatment 5C increased the interval to first progesterone rise and the number of services per conception relative to treatment OC. Cow parity, BF depth assessed at d 28 before parturition, and treatment provided the best fit relationships for the yields of fat and fat plus protein (R2 relationships = 0.65 and 0.64, respectively) during wk 1 to 4 of lactation. It was concluded that, other than milk fat concentration, supplementation with additional concentrates in late gestation did not alter milk yield or composition and dairy cow fertility. Furthermore, despite the very large differences in cow characteristics at d 28 before parturition, there was no evidence of any interaction between treatment and specific cow characteristics on animal performance in the first 12 wk of lactation.