Simultaneous detection of multiple mycotoxins in broiler feeds using a liquid chromatography tandem-mass spectrometry

Mycotoxins are secondary fungal metabolites that are typically present in grain and feed ingredients used for animal feeds. An analytical method using LC-ESI-MS/MS was developed to quantify nine mycotoxins, consisting of aflatoxin B₁ (AFB₁), AFB₂, AFG₁, AFG₂, T-2 toxin, deoxynivalenol (DON), nivalenol (NIV), zearalenone (ZEA) and ochratoxin A (OTA) in broiler feeds. In total, 100 samples of broiler feeds were collected from poultry farms in Central Thailand. The survey found that AFB₁ and ZEA were the most prevalent mycotoxins in the feed samples at percentages of 93% and 63%, respectively. The limit of detections (LODs) of investigated mycotoxins was 0.20–0.78 ng/g. AFB₂, DON, AFG₁, NIV and T-2 toxin were also detectable at low contamination levels with percentages of 20%, 9%, 7%, 5% and 1%, respectively, whereas OTA and AFG₂ were not detected in any of the feed samples. These results suggest that there is a very low level of risk of the exposure to mycotoxins in feeds obtained from broiler farms in Central Thailand.     

Effects of field pea (Pisum sativum L.) hay feeding on dry matter intake and milk production of Murrah buffaloes (Bubalus bubalis) fed rice straw ad libitum

To identify the effects of field pea hay (FPH) as a supplement of rice straw (RS) on feed intake and milk production of mid‐late lactation buffaloes in Tarai, Nepal, nine multiparous Murrah were fed a concentrate at 0.6% of their bodyweight (BW) on a concentrate dry matter (DM) basis daily while having ad libitum access to RS. The buffaloes were divided into three groups, and the experiment with three levels of FPH feeding was conducted at the following rate of BW: 0% (T1), 0.5% (T2) and 1.0% (T3) on an FPH DM basis. The DM intake (DMI) was higher in T2 and T3 than in T1. As the amount of FPH was raised, the BW change, crude protein intake (CPI) and total digestible nutrient intake (TDNI) was increased. Although the yield of milk and milk composition did not differ among the treatments, the 7% fat corrected milk yield (FCMY) tended to increase as FPH feeding amount was raised. Although there were no significant differences in FCMY/DMI and FCMY/TDNI among the treatments, FCMY/CPI decreased with FPH feeding. Supplementary FPH increased DMI, CPI and TDNI that might have raised BW, and tended to improve FCMY in mid‐late lactating buffaloes as a result of an increase in TDNI.     

Relationship between fish growth rate and progression of artificially induced erythrocytic inclusion body syndrome in coho salmon, Oncorhynchus kisutch (Walbaum)

Abstract. Studies were conducted to clarify the relationship between growth rate and disease progression of erythrocytic inclusion body syndrome (EIBS) in artificially infected coho salmon, Oncorhynchus kisutch (Walbaum). In the diseased state, the haematocrit values decreased and the number of erythrocytes with inclusions was higher in faster growing fish. Rapid growth was accompanied by an abundance of immature erythrocytes, which had the greatest incidence of inclusion bodies.     

Effects of plane of nutrition on growth,feed intake,digestibility and nitrogen balance in Murrah graded male buffalo (Bubalus bubalis) calves in Nepal

An experiment was conducted using 17 male buffalo calves to assess the effects of plane of nutrition on dry matter intake (DMI), daily gain (DG), body size measurement, apparent digestibility and nitrogen (N) balance. To attain 250 kg BW, the calves were allocated into three groups: H, L‐H and L, receiving the concentrate at 1.50% of BW, 0.75% of BW until 190 kg BW and 1.50% thereafter and 0.75% of BW, respectively. The animals had ad libitum access to urea‐treated rice straw (UTRS). The DMI of UTRS through the experiment was higher in L and L‐H than H, showing 3.52, 2.90 and 2.62 kg/day, respectively (P < 0.01), but the total DMI did not differ among the treatment groups. The DG throughout the experiment was high in the order of H, L‐H and L, showing 0.72, 0.57 and 0.45 kg, respectively (P < 0.01). The digestibility of DM, organic matter, crude protein, neutral and acid detergent fiber and N retention were higher in H than in L (P < 0.05). The findings of this study thus revealed the greater DG has an advantage of shortening the growing period around 3 months, and consequently increasing benefit in fattening of buffalo calves in Nepal.     

Effects of plane of nutrition on slaughtering traits and meat characteristics in Murrah graded male buffalo (Bubalus bubalis) calves in Nepal

An experiment was conducted using 17 male buffalo calves to assess the effects of plane of nutrition on slaughtering traits and meat characteristics. To attain 250 kg body weight (BW), the calves were allocated into three groups: high (H), low‐high (L‐H) and low (L) corresponding to concentrate levels receiving the concentrate at 1.50% of BW, 0.75% of BW until 190 kg BW and 1.50% thereafter, and 0.75% of BW, respectively. The animals had ad libitum access to urea‐treated rice straw. No significant differences of hot carcass weight, dressing percentage and lean fat–bone yields were observed among the treatment groups. The L group had heavier brisket weight and lower percentage of round weight in the hot carcass than the H and L‐H groups (P < 0.05). The H group had heavier hearts than the L group, and the H and L‐H groups had heavier livers and kidneys than the L group (P < 0.05). There was no significant difference of rib eye area, pH and the contents of moisture, crude protein and fat in loin meat among the groups. The findings indicated that the effects of plane of nutrition affected the weight or percentages of some cut yields in the hot carcasses and internal organs.     

Muscle tissue kinetics of oxytetracycline following intramuscular and oral administration at two dosages to giant freshwater shrimp (Macrobrachium rosenbergii)

The giant river shrimp (Macrobrachium rosenbergii), a native species of Thailand, is either exported for commercial purposes or supplied to meet the local requirements in Thailand. Limited pharmacokinetic information of the major antibiotic, oxytetracycline (OTC), is available for this freshwater shrimp. The purpose of the present study was to investigate the muscle tissue kinetics of OTC in M. rosenbergii following either intramuscular (i.m.) or oral (p.o.) administration at two dosages of 11 and 22 mg/kg body weight (b.w.). The concentration of OTC in shrimp tissues was measured using high‐performance liquid chromatography (HPLC) equipped with a fluorescence detector. Muscle tissue concentrations were below the detection limit (LOD, 0.1 μg/g) after 96 and 120 h, following i.m. and p.o. administration, respectively. Peak muscle concentrations (C_max) were 3.47 and 1.73 μg/g after i.m. and p.o. administration at a single dose of 11 mg/kg b.w. whereas they were 6.03 and 2.51 μg/g at a single dose of 22 mg/kg b.w., respectively. A noncompartment model was developed to describe the pharmacokinetics of OTC in the giant freshwater shrimp. The terminal half‐lives of OTC were 28.68 and 28.09 h after i.m. and p.o. administration at a single dose of 11 mg/kg b.w., but 29.95 and 27.03 h at a single dose of 22 mg/kg b.w., respectively. The relative bioavailability was 82.32 and 64.67% following i.m. and p.o. administration, respectively. Based on the pharmacokinetic data, i.m. and p.o. administration with OTC at a dose of 11 mg/kg b.w. would be appropriate for use in giant freshwater shrimp farming. To avoid the OTC residue in shrimp muscle, it should take at least seven half‐lives (8 days) to wash out the drug from the muscle of M. rosenbergii.     

Analyses of factors affecting dry matter intake of lactating dairy cows

An experiment was conducted to analyze feed, climate and animal factors affecting dry matter intake (DMI) in lactating dairy cows. Sixteen lactating Holstein cows, with parity from 1 to 6, were assigned to a feeding trial for 2 years, comprising 31 lactations. The animals were fed Italian ryegrass silage, oat hay, alfalfa hay, beet pulp and three types of concentrate. The data, pooled and classified by stage of lactation, season of lactation and parity were analyzed by stepwise multiple regression to determine the nature and extent of factors affecting DMI. A total of 45 prediction equations for DMI were derived. Energy‐corrected milk yield or milk yield was selected as the primary factor of DMI in all the equations in which the ratio of contribution (R²) varied from 0.26 to 0.67. The dietary concentration of organic cell wall, crude fiber, crude protein, organic b fraction, forage to concentrate ratio, average ambient temperature and temperature–humidity index were selected as the secondary factors affecting DMI for pooled data, late lactation (251–350 days of lactation), summer (June–August), spring (March–May), ≥4th lactation, autumn (September–November) and 3rd lactation, respectively, and improved R² up to 0.77. Except for an impact of bodyweight in several equations, feed and climatic factors significantly improved prediction equations effectively for data classified in different ways. To estimate DMI accurately in lactating dairy cows, feed and climatic factors should be considered for specific conditions.     

Effects of maize (Zea mays L.) silage feeding on dry matter intake and milk production of dairy buffalo and cattle in Tarai, Nepal

To identify the effects of whole crop maize silage (MS) as a substitute for rice straw (RS) on feed intake and milk production of mid-late lactating buffalo and cattle in Tarai, Nepal, eight Murrah and eight Jersey-Hariana were fed the basal diet, RS ( ad libitum ) with concentrate (0.68% of bodyweight [BW] on a dry matter [DM] basis). A 4 × 4 Latin square design experiment was conducted in each animal species with graded levels of MS substitution for RS (0%, T1; 33%, T2; 67%, T3 and 100%, T4). The MS had higher digestibility and total digestible nutrient (TDN) than RS. The DM intake per BW of the both species was highest in T3. The substitution of MS for RS increased the crude protein intake and the TDN intake in the both species. Although the buffalo showed the highest milking performance in T4, the cattle showed no significant differences in their milking performance among the treatments. The substitution of MS for RS improved the feed intake and milk production in the buffalo. On the other hand, the milk yield was not raised in the cattle, though the feed intake was increased by the substitution.     

Effects of adding food by‐products mainly including noodle waste to total mixed ration silage on fermentation quality,feed intake,digestibility, nitrogen utilization and ruminal fermentation in wethers

Four wethers were used in a 4 × 4 Latin square design experiment to evaluate the applicability of two types of total mixed ration (TMR) silage with food by‐products. Four food by‐products (i.e., potato waste, soy sauce cake, soybean curd residue and noodle waste) were obtained and mixed with commercial concentrate (CC) as TMR silage. The two types of TMR silage, T1 and T2, each contained CC, in addition to all by‐products for T1 (TRE1), and soy sauce cake and noodle waste for T2 (TRE2) on a dry matter (DM) basis. The silage was well‐fermented with low pH values and high lactic acid concentration. As the experimental treatments, T1, T2 and CC (CTL) were fed with a basal diet. The result showed that the digestibility of DM and organic matter (OM) were higher for T1 than for CC (P < 0.05), while crude protein digestibility was not significantly different among T1, T2 and CC. The retained nitrogen was not affected by inclusion of food by‐products. Ruminal pH in TRE1 and TRE2 immediately decreased compared to that in CTL. The study suggested that the two types of TMR silage, including food by‐products, might be used as a substitute for commercial concentrate.