Anna Hessle

A field survey on the status of internal parasites in calves on organic dairy farms in southwestern Sweden

Infections with internal parasites are one of the most important causes of reduced productivity in first-grazing season cattle (FGSC). In conventional herds, nematode infections can be controlled by prophylactic anthelmintic treatments, but this is prohibited in organic production. The purpose of this investigation was to monitor the status of internal parasitism on 15 organic cattle enterprises in southwestern Sweden during the 1997 and 1998 grazing seasons, and to estimate the benefits of some management practices in parasite control. On each farm, the numbers of Eimeria alabamensis oocysts per gram of (opg) faeces were counted in seven fresh dung pats collected from the paddock 8-10 days after the turnout of FGSC. Faecal samples from 5 to 15 FGSC were also analysed for nematode eggs per gram (epg) faeces at four occasions during each grazing season. In addition, the FGSC and one group of second-grazing season cattle (SGSC) were weighed at turnout and housing and at the same time blood samples were collected, and analysed for serum pepsinogen concentration and antibodies against the lungworm, Dictyocaulus viviparus. On seven farms, 1-6 samples with more than 100000 opg were found, indicating considerable pasture contamination by E. alabamensis. However, clinical signs of coccidiosis were not observed. The highest outputs of nematode eggs were observed 45-55 days after turnout. More than 500 epg were only observed in 12 (2.2%) of the calves in 1997 and in three (0.6%) animals in 1998. Only 1% of the serum samples had pepsinogen values exceeding 3.6 U tyrosine, indicative of subclinical Ostertagia ostertagi infection. Lungworm infection was detected in five and nine herds in 1997 and 1998, respectively. The number of seropositive animals on these farms ranged between one (10%) and seven (70%). Clinical signs of dictyocaulosis were observed on two farms. The results indicate that dictyocaulosis is a problem in organic dairy herds in Sweden. On the other hand, the study shows that good management such as usage of parasite safe pastures and supplementary feeding may help control gastrointestinal parasites.

Parasite control methods in organic and conventional dairy herds in Sweden

Abstract The objectives of this study were to compare methods of parasite control and to get an indication of the magnitude of parasite infections in organic and conventional dairy herds in Sweden. In February 1997, a questionnaire with mainly multiple choice alternatives was distributed to 162 organic and 162 conventional dairy farms in central Sweden. The response rates were 84% and 72%, respectively. A majority (58%) of the conventional farmers reported that their animals were treated prophylactically, mainly with controlled-release intraruminal devices. In organic production, parasite control methods involving grazing management combined with nutritional supplementation with concentrates and/or forage was the most frequently reported anti-parasite strategy. The most common procedure was to turn calves out on pastures not grazed by any cattle in the current or previous grazing seasons. This was employed by significantly more organic than conventional farms (40% vs. 3%), as was alternating grazing with other livestock species (27% vs. 3%). Sixty percent of the organic and 52% of the conventional farmers reported that they used nutritional supplementation in the autumn, and 48% and 29% of the producers, respectively, that they used nutritional supplementation in the spring, as methods to restrict parasite problems in their calves. Outbreaks of diarrhoea in first grazing season cattle and a lower weight gain during the grazing season than in the previous winter season, problems that may be due to parasite infections, were reported more frequently from organic herds. Despite an apparently increased awareness of various worm control strategies, organic farmers thus seemed to have greater problems with parasite infections than did conventional farmers.

Antibodies to major pasture borne helminth infections in bulk-tank milk samples from organic and nearby conventional dairy herds in south-central Sweden

The objective of this randomised pairwise survey was to compare the regional distribution of antibody levels against the three most important helminth infections in organic and conventional dairy herds in Sweden. Bulk-tank milk from 105 organic farms and 105 neighbouring conventional dairy farms with access to pasture in south-central Sweden were collected in September 2008. Samples were also collected from 8 organic and 8 conventional herds located in a much more restricted area, on the same as well as 3 additional occasions during the grazing season, to reveal evidence for seasonal patterns against cattle stomach worm (Ostertagia ostertagi). Antibody levels to the stomach worm (O. ostertagi), liver fluke (Fasciola hepatica) and lungworm (Dictyocaulus viviparus) were then determined by detection of specific antibodies using three different enzyme-linked immunosorbent assays (ELISAs). According to the Svanovir Ostertagia ELISA, the mean optical density ratio (ODR) was significantly higher in the milk from organic compared to conventional herds, i.e. 0.82 (95% CL=0.78-0.86) versus 0.66 (0.61-0.71). However, no significant differences were observed in the samples collected at different time points from the same 16 herds (F(3,39)=1.18, P=0.32). Antibodies to D. viviparus infection were diagnosed with an ELISA based on recombinant major sperm protein (MSP), and seropositivity was found in 21 (18%) of the 113 organic herds and 11 (9%) of the 113 conventional herds. The seroprevalence of D. viviparus was somewhat higher in the organic herds (Chi-square=3.65, P=0.056), but with the positive conventional herds were located in the vicinity of infected organic herds. Of the 16 herds that were sampled on repeated occasions, as many as 10 (63%), were seropositive on at least one sampling occasion. Many of these turned positive towards the end of the grazing season. Only one herd was positive in all 4 samples and 3 were positive only at turn-out. Considering F. hepatica there was no difference in seroprevalence between organic and conventional herds according to the Institute Pourquier ELISA. In general, liver fluke infection was low and it was only diagnosed in 8 (7%) organic and 7 (6%) conventional herds.

Weight gain-based targeted selective treatments (TST) of gastrointestinal nematodes in first-season grazing cattle.

A three-year trial was performed in south-western Sweden to compare animal performance and levels of parasite control in three grazing groups, each with 18-24 first-season grazing (FSG) calves in similar set-stocked pasture enclosures. These groups were subjected to: (1) no parasite control (NT), (2) monthly repeated doramectin (Dectomax(®)) injections (SP), or (3) targeted selective weight gain-based anthelmintic treatments (TST) but only when individual calf performance was inferior to the average of the poorer 50% of those calves in group SP. In each year, weight and parasitological variables were measured at turn-out and then at predetermined intervals for 22-24 weeks during the grazing season. The dewormed calves in group SP had a higher average weight gain at housing (range 0.39-0.61 kg/day) than those in TST (0.36-0.50 kg/day), which in turn always exceeded the NT group (0.23-0.42 kg/day). This indicates that the parasite challenge in the NT group was sufficiently high to result in production loss. However, the average cumulative faecal egg counts (FEC) at housing in NT were in the range 1271-1953 eggs per gram faeces (epg) and in TST 1221-1968 epg. In contrast, parasite eggs were rarely recorded in group SP and then only during the first two years (on average 12 and 38 epg). There were also no significant differences in FEC or serum pepsinogen levels between FSG in groups NT and TST. The animals in SP received 7 doses of doramectin each year, whereas those in TST received an average of 0.5 doses. Thus, the TST approach represented a 92% reduction in anthelmintic use. The average weight gain in animals subjected to TST was always significantly lower than in animals dewormed regularly. In addition, there were no signs of short-term selection for anthelmintic resistance in the group SP animals, despite the fairly intensive use of injectable doramectin.

Cold-pressed hempseed cake as a protein feed for growing cattle

Abstract Cold-pressed hempseed cake was investigated as a protein feed for young calves and finishing steers. Half of the animals were fed cold-pressed hempseed cake, whereas the other half were fed a mixture of soybean meal and barley. Effects on feed intake, liveweight gain (LWG), faecal traits and carcass traits (steers only) were studied. Neutral detergent fibre intake was higher for animals fed hempseed cake than for those fed soybean meal (P<0.05). In addition, the number of long particles in faeces was lower (P<0.05) and faecal dry matter content and consistency were higher from animals which were fed hempseed cake (P<0.05; steers only). Higher feed intakes in calves fed hempseed cake (P<0.05) combined with similar LWG resulted in lower feed efficiency in hemp-fed calves (P<0.05). In conclusion, hempseed cake compared to soybean meal as a protein feed for intensively fed growing cattle results in similar production and improved rumen function.

Influence of carcass suspension on meat quality of Charolais heifers from two sustainable feeding regimes.

This study investigated the effects of pelvic suspension on the meat quality of M. longissimus dorsi, M. semimembranosus and M. adductor from 35 heifers with at least 75% Charolais breeding. Two-thirds of the heifers were slaughtered directly from pasture at 18 months of age and one-third was finished indoors and slaughtered at 22 months. After slaughter and electrical stimulation one side of each carcass was re-suspended by either the achilles tendon or the pelvic bone. Longissimus muscles were aged 7 or 14 days and were then evaluated for drip loss, colour, shear force and sensory analysis. As compared to 18-month-old heifers, 22-month-old heifers were heavier, more muscular and fatter (P < 0.05). Intramuscular fat content increased with slaughter age (P < 0.003). Pelvic suspension reduced longissimus peak force values, total energy, pH and thawing losses (P < 0.05) in heifers slaughtered at 18 months. Semimembranosus showed the largest response to pelvic suspension with significantly lower peak force and total energy values. Finishing for 4 months did not affect longissimus shear forces. Achilles-suspended samples had lower shear force values after 14 v. 7 days of ageing. Pelvic-suspended samples aged 7 days were, however, just as tender as those aged 14 days. Sensory analysis of longissimus samples aged 14 days showed that samples from pelvic-suspended sides had higher tenderness, lower bite resistance, more meaty taste and less visible marbling compared with samples from achilles-suspended carcasses.

Feeding dairy calves and replacement heifers in South-western Sweden: a survey

Daily feed rations, their nutrient contents and live weight gains were recorded for calves and replacement heifers from birth to calving in 122 Swedish dairy herds. Preweaned calves were fed whole milk (45% of the herds), milk replacer alone or milk replacer combined with whole milk. Calf starters were the most frequently used concentrates for preweaned calves, whereas grain dominated for weaned calves and heifers. Grain was supplemented with protein concentrates until 6 months of age and at calving. Grass/clover hay was the dominant forage for preweaned calves, whereas grass/clover silage alone or in combination with hay was the most common forage for calves and replacement heifers from 6 months of age. Heifers grazed semi-natural grasslands, leys or a combination of semi-natural grasslands and leys in 33, 15 and 52% of the herds, respectively. According to Swedish recommendations, calves in a majority of the herds were fed too low concentrations of crude protein from weaning to 6 months of age and calves were fed too low a metabolizable energy content inadequate for a daily weight gain of 700 g at weaning. Median live weight gain from birth to calving was only 567 g per day. Correct feed ration formulations and strategic grazing management could be means to increase weight gain and hence to decrease rearing costs of calves and replacement heifers in Swedish dairy herds.

Influence of slaughter age and carcass suspension on meat quality in Angus heifers

This study investigated the effects of pelvic suspension and slaughter age on longissimus thoracis et lumborum (LTL) from 40 heifers with at least 75% Angus breeding. A total of 20 heifers were slaughtered directly from pasture at 18 months of age, and carcass sides were hung either by the Achilles tendon or the pelvic bone. The other 20 heifers were assigned to an additional winter housing period and slaughtered at 22 months of age; carcass sides were hung only by Achilles suspension. All carcasses were electrically stimulated and assessed according to the EUROP carcass classification system. In addition, the LTL muscles were aged for 7 or 14 days before meat quality was evaluated for intramuscular fat (IMF), drip loss, colour, shear force, compression and sensory analysis. The 22-month-old heifers were heavier, fatter and had more IMF than 18-month-old heifers. Conformation scores (muscling) did not differ between the two slaughter groups. Pelvic suspension reduced both between- and within-animal variation for peak force, total energy and compression peak force. For the 18-month-old heifers, pelvic suspension also decreased peak force, total energy and compression variables for the LTL muscles from both ageing periods, whereas Achilles-suspended samples had lower shear force values only at day 14. Sensory analysis showed that pelvic-suspended sides had greater tenderness, lower bite resistance, less threadiness, higher juiciness and meat flavour and less visible marbling than meat from Achilles-suspended sides. Pelvic-suspended sides at 18 months of age were similar in peak force and total energy values to the 22-month-old heifers. The importance of ageing the Achilles-suspended sides was more obvious for samples from 18-month-old heifers than from the 22-month-old animals. The correlations between the different instrumental measurements and sensory tenderness were considerably higher for carcasses suspended by the Achilles tendon (r = -0.55 to 0.20) than for those hung by the pelvic bone (r = -0.25 to 0.19). More correlations between sensory-evaluated tenderness and shear variables were significant after 7 days (n = 6) of ageing than after 14 days (n = 4) of ageing. This study clearly shows the benefits of pelvic suspension, which reduces the need for additional feeding after pasture.

Effects of breed on foraging sites and diets in dairy cows on mountain pasture

Biodiverse semi-natural pastures are threatened because of sub-optimal grazing. Breed effects on choice of foraging vegetation type, diet and hence pasture management was investigated in dairy cows kept on mountain pastures. Five dairy cows each from the traditional Swedish Mountain breed and the commercial Holstein breed were equipped with GPS receivers measuring animal position for 6 h daily grazing time during 6 days. Plant groups in ingested vegetation were recorded visually for 30 min per cow and day. The grazing area, mapped using infra-red aerial photography combined with field work, consisted of ten vegetation types dominated by bilberry forest (33%), mixed forest (28%) and grass and sedge fen (12%). Although grass-dominated pasture comprised only 0.3% of the area, the cows spent, on average, 27% of their time there. Swedish Mountain cows spent less time in grass-dominated pasture than Holsteins (24% vs. 31%, p = 0.035). Swedish Mountains also travelled longer distances (6.3 vs. 5.0 km, p = 0.016) and were scattered over longer distances from other cows (419 vs. 259 m, p = 0.011). This limited study revealed a general selection of grass-dominated pasture, but indicated that using traditional breeds can result in better management of other vegetation types.

Influence of hempseed cake and soybean meal on lipid fractions in bovine M. longissimus dorsi

Abstract Sixteen Swedish Red steers were fed a hempseed cake (HC) or soybean meal (SM) protein supplement. Lipid extract from fresh and cooked M. longissimus dorsi were analysed. Diet comparison showed that HC had increased monounsaturated fatty acid proportion, primarily 18:1 cis-9 in the meat (P<0.05). Additionally, HC steers had higher proportions of 18:1 trans-11 and 18:2 c-9, t-11 (P<0.05). Furthermore, HC steers had decreased n-6/n-3 fatty acid ratio compared to SM steers (P<0.05). Cooking increased polyunsaturated fatty acid (PUFA) and n-6 level, particularly 18:2n-6 and 20:4n-6 (P<0.05). Cooking decreased the proportion of 17:0 and 18:0 (P<0.05). In polar lipid, HC steers had lower saturated fatty acid (P<0.05) and higher PUFA levels (P<0.05). Warner-Bratzler shear force and lipid content were unaffected by dietary treatment. Cooking decreased the triacylglycerol level of both groups (P<0.01). We conclude that HC is a viable alternate supplement for beef diets which improves the meat FA profile.