Mycotoxin incidence in forage may heavily affect the amount of toxins consumed by cattle. However, many studies have focused on mycotoxin occurrence in cereals and there are less studies of forages, particularly of grass silages. For determining the occurrence of mycotoxins in farm silages under Northern European conditions in Finland, 37 grass silage and 6 whole-crop cereal silage batches were analysed separately for surface, core and, if present, visibly mouldy spots. Mycotoxins were found in 92% of the samples. All mouldy samples contained mycotoxins. Beauvericin was the most common mycotoxin in grass silages and roquefortine C in whole-crop cereal silages. In mouldy samples, beauvericin, mycophenolic acid and roquefortine C were the most common mycotoxins in the grass silage and mycophenolic acid in the whole-crop cereal silage. Aflatoxins were not found in any of the samples. On average, all samples contained more than one type of mycotoxin. Concentrations of mycotoxins varied considerably from very low to very high values. The results of this survey indicate that silage-fed ruminants can be exposed to a broad range of mycotoxins. The absence of visible moulds does not always indicate mycotoxin-free feed. All moulded samples contained mycotoxins and some at very high concentrations, and they contained more different types of mycotoxins than samples without visible mould. Thus, feeding mouldy feeds to animals should be avoided.

The effects of different barley grain preservation techniques on intake, growth and carcase traits of dairy bulls were determined in a feeding trial using 52 Holstein and 48 Nordic Red bulls which were allotted to four feeding treatments (five pens and 25 bulls per treatment). Spring barley was harvested with a conventional combine harvester and four different preservation techniques formed the four experimental treatments. Dry grain (DG) was dried to the targeted dry matter (DM) concentration of 870–880 g/kg and rolled within 7 days prior to feeding. High moisture grain treated with a formic acid-based additive (FA) was harvested and crimped on the targeted DM content of 700 g/kg. Low moisture grain treated with a urea-based additive (UR) and low moisture grain treated with a propionic acid-based additive (PA) were harvested and crimped on the targeted DM content of 800 g/kg. The bulls were fed with total mixed ration ad libitum. On DM basis, the diets included grass silage (500 g/kg), barley grain (485 g/kg) and a mineral–vitamin mixture (15 g/kg). Daily DM intake (DMI) and live weight gain were 6% higher when crimped grains were used instead of DG (P < 0.05). There were no observed significant differences in DMI, gain or carcase traits between high moisture and low moisture crimped grain treatments or between UR and PA. The current results show that producers have the option to vary grain preservation system without major changes to growth performance or carcase traits.

When targeting low-carbon feed production and feeding cattle with non-human-edible feeds, in practice, this means maximising the use of forages such as grass. However, there is a gap in knowledge of the environmental impacts when carcass weight increases and/or concentrate is excluded from grass silage (GS)-based diet. The objective of this study was to evaluate the effects of two different GS-based diets and three carcass weights on performance and environmental impacts of growing heifers. The experiment was conducted using 84 crossbred heifers (Holstein or Nordic Red × Blonde d'Aquitaine). Two experimental diets were GS alone (GSA) and GS supplemented with barley grain (285 g/kg DM; GSB). Both diets contained a mineral-vitamin mixture (15 g/kg DM). The heifers were fed total mixed rations ad libitum. The animals were slaughtered at three BWs, targeting carcass weights of 300 (LCW), 325 (MCW) or 350 (HCW) kg. Life cycle assessment approach was used to compare climate change, eutrophication, and acidification impacts for both feeding treatments across three carcass weights. The experimental treatments had no effects on daily DM intake, but total DM intake was 13% higher for the GSA compared to GSB (P < 0.001) and 37% higher for HCW compared to LCW (P < 0.001). Barley grain supplementation increased daily energy intake by 14% (P < 0.001). Excluding barley grain from the diet decreased carcass gain by 20% (P < 0.001). Feed conversion (kg DM/kg carcass gain) declined when barley grain was excluded from the diet (P < 0.001). Carcass weight had no effect on growth rate and feed conversion. For GSA, the dressing proportion was 3% (P < 0.001) and carcass conformation 11% (P = 0.018) lower compared to GSB, but they were not affected by carcass weight. For carcass fat score, feeding × carcass weight quadratic interaction was observed (P < 0.016). Compared to GSA, GSB animals were fatter and carcass fat cover was affected to a greater extent by carcass weight. At the same carcass weight, the climate change impact of GSB was 10-11%, eutrophication potential 13-15%, and acidification potential 20-23% lower compared to GSA. Increasing carcass weight raised all impacts by 4-9% per functional unit within both dietary treatments. For all carcass weights, GSB showed consistently lower environmental impacts than GSA. In conclusion, including concentrate in the diet improved performance of the heifers and decreased environmental impacts.

Residual feed intake (RFI) is the preferred measurement for feed efficiency in beef cattle, but it is laborious to determine. Data from two experiments of growing bulls (test period durations of 56 and 63 days) were used to examine how a reduction in the number of times the animals were weighed and the shortening of the length of the observation period affect the reliability of the RFI determination. We introduce two easily understandable probability measures for assessing reliability. ‘The consistency of the pair-wise ranks’ gives the probability that the rank of any two animals compared remains the same when the amount of data is reduced. ‘The consistency of the thirds’ gives the probabilities that an individual animal will remain in the same, i.e., the lowest, middle, or highest, third of animals. The reliability of the results was not greatly affected when the weighing interval was reduced from one week to four weeks. However, shortening the test period resulted in a marked reduction in the reliability of RFI. If individual feed intake is automatically measured, the workload required for RFI measurements can most effectively be reduced by reducing the number of weighing times but keeping the duration of the test period long enough.