Differences In Liveweight Gain Research Articles

Behavioural response to gastrointestinal parasites of yearling dairy calves at pasture

ABSTRACT Aims To investigate the association between gastrointestinal parasites (GIP) and animal behaviour in dairy calves under New Zealand pastoral conditions, using animal-mounted, accelerometer-based sensors. Methods Thirty-six, 5–6-month-old, Friesian-Jersey, heifer calves fitted with animal activity sensors to track behaviour were randomly allocated to one of two treatment groups. Half the animals were challenged with an oral dose of 20,000 larvae of Ostertagia ostertagi and Cooperia oncophera once a week for 3 weeks and half were unchallenged. Five weeks after the last dose, seven infected and nine uninfected animals were treated with an oral anthelmintic (AHC) and data collected for a further week. Accelerometer data were classified into minutes per day eating, ruminating, in moderate–high activity or in low activity. Live weight and faecal egg counts (FEC) were recorded weekly over the study period. All animals co-grazed a newly sown pasture not previously grazed by ruminants and were moved every week to fresh grazing. Treatment status was blinded to those managing the animals which were otherwise treated identically. Results Complete behavioural records were available from 30/36 calves, (13 challenged and 17 unchallenged). Before treatment with AHC, FEC increased in infected and un-treated calves over the study, while uninfected animals maintained a near zero FEC. There was no difference in live weight gain between the two groups over the study period. Bayesian, multinomial regression predicted differences in animal behaviour between infected and uninfected animals that were not treated with AHC over the 7 weeks following initial infection. Parasitised calves not treated with AHC were less active and spent up to 6 (95% highest density interval (HDI) = 1–11) minutes/day less in low level activity and up to 15 (95% HDI = 7–20) minutes/day less in moderate to high level activity. They ruminated up to 9 (95% HDI = 2–15) minutes/day more and ate up to 10 (95% HDI = 2–19) minutes/day more than control calves that were not treated with AHC. The effect of AHC on time spent in each behaviour differed between infected and uninfected calves and increased the coefficient of dispersion of the behavioural data. Conclusions and clinical relevance Small differences in animal behaviour can be measured in calves with GIP. However, to use this to target treatment, further validation studies are required to confirm the accuracy of behavioural classification and understand the complex drivers of animal behaviour in a dynamic and variable pasture-parasite–host environment.

Grazing management and stocking strategy decisions for pasture-based beef systems: experimental confirmation vs. testimonials and perceptions

Abstract Grazing management and stocking strategy decisions involve the manipulation of grazing intensity, grazing frequency, and timing of grazing to meet specific objectives for pasture sustainability and economic livestock production. Although there are numerous stocking systems used by stakeholders, these methods may be broadly categorized as either continuous or some form of rotational stocking. In approximately 30 published experiments comparing continuous vs. rotational stocking, there was no difference in liveweight gain per animal between stocking methods in 66% of studies. There was no difference in gain per hectare between methods in 69% of studies, although for gain per hectare the choice of fixed or variable stocking rate methodology affected the proportion (92% for fixed; 50% for variable). Despite these experimental results showing limited instances of difference between rotational and continuous stocking, rotational strategies (e.g., “mob stocking” or “regenerative grazing”) have received what appears to be unmerited acclaim for use for livestock production. Many proposed “mob stocking” or “regenerative grazing” systems are based on philosophies similar to high intensity-low frequency stocking, including provision for >60 d of rest period from grazing. In addition, grazing management practitioners and stakeholders have voiced and proposed major positive benefits from rotational stocking, “mob stocking”, or “regenerative grazing” for soil health attributes, carbon sequestration, and ecosystem services, without experimental evidence. The perceptions and testimonials supporting undefined stocking systems and methods have potential to mislead practitioners and result in economic disservices. Thus, we suggest that scientists, extension-industry professionals, and producers seek replicated experimental data as the basis for predicting outcomes of grazing decisions.

Influence of Probiotic Strains Bifidobacterium, Lactobacillus, and Enterococcus on the Health Status and Weight Gain of Calves, and the Utilization of Nitrogenous Compounds.

The aim of this study was to monitor the effect of Bifidobacterium bifidum (BB) and the combination of Lactobacillus sporogenes, Enterococcus faecium, and Bifidobacterium bifidum (LEB) on the health status and weight gain of calves, and the utilisation of nitrogenous substances. The experiment was performed in the period from April 2020 to September 2020. A total of 90 Holstein heifers, which were one to 56 days old, were used as experimental animals. Differences in live weight gain were significant if we compared the LEB vs. BB group and the LEB vs. C, the control group (86.23 ± 5.49 kg vs. 84.72 ± 6.22 kg, p < 0.05; 86.23 ± 5.49 kg vs. 82.86 ± 5.35 kg, p < 0.01). Considering the live weight gain, group BB was heavier than group C only (84.72 ± 6.22 kg vs. 82.86 ± 5.35 kg, p < 0.05). An effect on reducing the incidence and duration of diarrheal diseases was not demonstrated in this study (p = 0.1957). The administration of feed additives had no statistically significant effect on the amount of N excreted in the feces. The values of hematological and biochemical parameters were unaffected except for the first sampling of urea. Other blood parameters were not affected by the addition of probiotic feed additives. The bacterial populations in the feces 5 days and 56 days after birth were not affected by the inclusion of feed additives.

The production costs of Haemonchus contortus and other nematode parasites in pre-weaned beef calves in New Zealand.

Haemonchus contortus can frequently be found infecting pre-weaned beef calves on sheep and beef farms around the North Island of New Zealand. The purpose of this study was to consider whether the presence of this parasite alone, or as part of a mixed infection, could be impacting growth rates of young animals, on three commercial farms in the North Island of New Zealand. Trials were conducted on commercial sheep and beef farms in each of the Northland, King Country and Gisborne regions, in late summer/autumn (February to April) of 2016 to measure the effect of treatment with narrow and broad spectrum anthelmintics on liveweight gain of spring-born calves pre-weaning. Each farm was chosen based on the presence of Haemonchus and that it was a beef cow/calf system with the cows and calves grazing the same pastures as sheep at some stage. Three sampling visits were made to each farm with the animals being weighed, faecal sampled and treated with one of two anthelmintics (Closantel alone to remove only Haemonchus or a triple combination containing moxidectin, levamisole and oxfendazole to remove all nematodes) or left untreated, on each of the first two visits. There was no significant difference in liveweight gain between any of the treatment groups, hence there was no evidence for an impact of Haemonchus alone, or a mixed nematode infection, on pre-weaned calf growth rates on these farms. It remains unclear whether there may be a justification to consider treatment of calves should they constitute a significant source of pasture larval infestation with H. contortus, in an integrated cattle-sheep system.

EFFECT OF OUTDOOR ACCESS ON ETHOLOGICAL BEHAVIOR, HEALTH AND PERFORMANCE OF BROILERS IN THE TROPICAL MEXICAN CONDITIONS

&lt;p&gt;&lt;strong&gt;Background. &lt;/strong&gt;There is a concern among poultry meat consumers due to broiler conditions during rearing period in commercial production systems. Consumers trust the organic and free-range poultry production systems because they suppose are more suitable and natural, giving high nutritive value and low-fat content to the meat, improving also the chicken welfare.&lt;strong&gt; Objetive.&lt;/strong&gt; Two studies evaluated the effect of an outdoor access on ethological behavior, health indicators and productive performance of Hubbard broilers in the rearing period. &lt;strong&gt;Methodology.&lt;/strong&gt; The first experiment evaluated outdoor access system in spring (april to may), and the second one was implemented in summer (june to august). In both studies included two groups: a) chickens with outdoot access (OA) and b) chickens at indoor rearing only (WOA). In the first experiment, ethological behaviors (EB) were described; forage intake (Fo), feed intake (FI), live weight gain (LWG) and carcass characteristics (Cc) were measured, blood components (BC), total immunoglobulins (Ig) and parasite eggs counts in excreta (Pc) were also determined, besides microscopic gut lesions in chickens (ML) were evaluated. In the second experiment, live weight gain (LWG), feed intake (FI) and forage intake (Fo) were measured, also carcass characteristics (Cc) were determinated. Analysis of variance by one way ANOVA was performed. &lt;strong&gt;Results.&lt;/strong&gt; In first experiment, it was found that OA and WOA chickens stayed the most time resting. However, inside and outside, moving and foraging behaviors were observed in OA, while in WOA treatment foraging of chickens was the less frequent conduct. WOA showed higher final live weight and FI, but there were no differences in LWG and feed conversion in comparison with OA. Gizzard and caeca weights were heavier in OA treatment. No differences in both carcass yield and abdominal fat were found. At the last two weeks of age the forage intake amount per bird was 1.93 &lt;span style="text-decoration: underline;"&gt;+&lt;/span&gt; 0.97 g and 2.06 &lt;span style="text-decoration: underline;"&gt;+&lt;/span&gt; 0.87 g of DM/d of &lt;em&gt;Leucaena leucocephala&lt;/em&gt; and&lt;em&gt; Pennisetum purpureum&lt;/em&gt;,&lt;em&gt; &lt;/em&gt;respectively. OA chickens had fewer leukocytes number (lymphocytes, eosinophils) and total inmmunoglobulins, but more heterophils and blood hemoglobulin. No differences between treatments in &lt;em&gt;Eimeria&lt;/em&gt; oocysts in excreta were found. However, higher distribution and severity in microscopic gut lesions in birds WAO treatment were found. While in second experiment it was found that both OA and WAO broilers had similar final weight, feed intake, carcass yield and abdominal fat, but OA chickens had a trend to be higher in both weight gain and better feed convertion. Likewise, AO and WAO broilers had similar tibial ash content. Also, AO broilers consumed 0.50 &lt;span style="text-decoration: underline;"&gt;+&lt;/span&gt; 0.36; 0.49 &lt;span style="text-decoration: underline;"&gt;+&lt;/span&gt; 0.50 and 0.60 &lt;span style="text-decoration: underline;"&gt;+&lt;/span&gt; 0.32 g of DM/d of &lt;em&gt;Leucaena leucocephala&lt;/em&gt;, &lt;em&gt;Brosimum alicastrum&lt;/em&gt; and &lt;em&gt;Moringa oleifera&lt;/em&gt;,&lt;em&gt; &lt;/em&gt;respectivily. &lt;strong&gt;Implications.&lt;/strong&gt; It is basic to have the knowledge regarding poultry production with outdoor access in tropical conditions. &lt;strong&gt;Conclusions.&lt;/strong&gt; Outdoor access stimulated natural behaviours expression and did not affect productive performance. Also, AO did not produce hematological changes or severe microscopic lesions.&lt;/p&gt;

Effects of Spirulina (Algae) supplementation to Japanese Quail (Coturnix coturnix Japonica) diets on growth performance and carcass traits

This study was conducted to determine the effects of spirulina (Sipurulina platensis) (SP) supplementation to quail ration on bird live weights, change in live weight, feed consumption, feed conversion ratio, carcass yield and serum biochemical parameters. A total of 220 Japanese quail chicks (Coturnix coturnix japonica) were used in experiments. There were 4 treatment groups including a control group with 55 birds in each group. Each group was divided into 5 sub-groups with 11 birds in each. Experiments were conducted for 35 days. Control group was fed with a basal ration. Treatment groups were fed with spirulina-supplemented (1, 2 and 4%) rations. Spirulina supplementations had significant effects on live weights. However, differences in live weight gain, feed consumption, feed conversion ratio and carcass yields were not found to be significant. SP supplementation did not have significant effects on serum total cholesterol, glucose, protein, triglyceride and uric acid concentrations. Although different spirulina supplementations yielded similar growth performance and carcass traits with the control treatment, it can still be stated that such treatments slightly improved growth performance and carcass traits of quail.

Effect of dietary protein levels on growth performance, hematological profile and biochemical composition of fingerlings rainbow trout, Oncorhynchus mykiss reared in Indian himalayan region

A 10-week feeding trial was undertaken to determine the optimum dietary protein requirement of fingerling rainbow trout, Oncorhynchus mykiss. Six casein-gelatin based isocaloric (20.90 kJ 100 g−1, gross energy) diets containing graded levels of dietary protein (300–550 g kg−1 crude protein) were formulated. Twenty fingerlings (1.56 ± 0.22 g; 5.80 ± 0.50 cm) were randomly stocked in triplicate groups in 75 L circular trough fitted with continuous flow-through system (water volume 2–2.5 L−1) and fed experimental diets at 5% BWday−1 at 0800, 1200 and 1700 h. Significant (P < 0.05) differences in live weight gain, specific growth rate (SGR), feed conversion ratio (FCR), protein efficiency ratio (PER) and body protein deposition (BPD) were noted. Quadratic regression analysis of SGR, FCR, PER and BPD data indicated requirements for dietary protein at 464.5, 471.0, 444.0 and 449.6 g kg−1 of dry diet, respectively. Maximum protein, low moisture and intermediate body fat contents were recorded with fish fed at 450 kg−1 protein diet, while highest HSI value was observed at lowest protein level. Significant differences (P < 0.05) were also observed in Hb, Hct and RBC values of fish fed varying protein diets. Based on the above results, it is recommended that rainbow trout fingerlings require protein in the range of 450–471 g kg−1 for its optimum growth and efficient feed utilization.

Yaz Koşullarında Gece-Gündüz Yemlemesi ve Aydınlatmanın Etlik Piliçlerin Performansı Üzerine Etkileri

Yaz koşullarında etlik piliçlerde gece-gündüz yemlemesi ve aydınlatmanın performans üzerine etkileri toplam 1104 adet ticari etlik civciv kullanılarak araştırılmıştır. Denemenin ikinci haftasında, etlik piliçler erkek-dişi ayrı olmak üzere 2 × 6 tekerrürlü olmak üzere deneme bölmelerine yerleştirilmişlerdir. Denemede, kontrol grubuna (1. grup) sürekli aydınlatma ve serbest yemleme yapılmıştır. 2. gruba sürekli aydınlatma uygulanmış ve son üç hafta 10:00 ile 16:00 saatleri arasında aç bırakılmıştır. 3. gruba ise sürekli aydınlatma yapılmış ve deneme süresince gündüz 10:00 ile 16:00 saatleri arasında aç bırakılmıştır. 4. gruba günışığı dışında sürekli aydınlatma yapılmış ve gece 24:00 ile 06:00 saatleri arasında yem verilmemiştir. 5. gruba sürekli aydınlatma uygulanmış ve son üç hafta gece 24:00 ile 06:00 saatleri arasında yem verilmemiştir. 6. gruba ise gündüz yem verilmiş, gece ise karartma yapılarak 24:00 ile 06:00 saatleri arasında yem verilmemiştir. Deneme sonunda her iki cinsiyette de muameleler arasında canlı ağırlık artışı, yem tüketimi ve yemden yararlanma oranı bakımından farklılık istatistikî olarak önemsiz bulunmuştur. Sıcak-soğuk karkas ağırlığına erkek-dişi etlik piliçlerde muamelelerin etkisi önemli olup, erkeklerde 3. ve 6. muamele grupları, dişilerde ise 6. muamele grubu daha yüksek bulunmuştur. Erkek etlik piliçlerde karkas randımanına muamelenin etkisi önemli bulunmuş, 4. ve 6. muamele gruplarının en yüksek değere sahip olduğu saptanmıştır. Dişi etlik piliçlerde ise karkas randımanı bakımından muameleler arasında farklılık bulunmamış. Muamelelerin ölüm oranlarına olan etkisi de önemsiz bulunmuştur. Yaz koşullarında serbest yemleme ve sürekli aydınlatma uygulaması piliçlerin performansını olumsuz etkilerken, kısıtlı yemleme ve aydınlatma ise hayvanların verim kayıplarını göreceli olarak azaltmıştır.

Acute and sub-acute toxicity evaluation of Enterococcus faecalis HZNU P2 isolated from peacock faeces in vivo

The sub-acute toxicity of E. faecalis HZNU P2 was investigated in rats fed with different doses for 14 days. To evaluate the acute oral toxicity of E. faecalis HZNU P2, rats were fed with E. faecalis HZNU P2 at a high dose of 2×1011 CFU kg−1 for 10 days. Results showed that there were no abnormal clinical signs in any of the groups during the experiment. There were no significant differences in live weight gain among rats fed with E. faecalis HZNU P2, compared to those in control group. Macroscopic or microscopic examinations of organs revealed no abnormalities, indicating that E. faecalis HZNU P2 did not adversely affect the health of rats. Results of this study demonstrated that digestion of E. faecalis HZNU P2 in rats did not show any obvious signs of toxicity.

Variation in feed utilisation by sheep undergoing compensatory growth following underfeeding with and without additional dietary nitrogen in western China

Small mixed farming systems in developing economies often rely on compensatory growth to recover livestock weight lost during seasonal feed shortages; however, deficit feed management may continue to affect the capacity of livestock to efficiently use feeds even after adequate feeding has resumed. Accordingly, we compared the difference in liveweight gain and feed utilisation over time in Tan weaner sheep in western China, during a period of ad libitum compensatory feeding after alternative feed deficit scenarios. During the feed deficit period, sheep were offered, at 80% maintenance requirements, corn straw, corn grain and lucerne hay in a respective ratio of either 80 : 20 : 0 (S1 ration: metabolisable energy = 7 MJ/kg DM, crude protein = 40 g/kg DM) or 55 : 20 : 25 (S2 ration: metabolisable energy = 8 MJ/kg DM, crude protein = 65 g/kg DM) for 20 days. All sheep were then offered an ad libitum supply of the S2 ration for a further 20 days, during which DM digestibility (DMD), energy intake and liveweight was measured and compared at 5-day intervals. Results indicated that sheep previously fed the S1 ration were not able to digest as much of the ad libitum S2 ration as those previously fed the S2 ration, experiencing significantly lower DMD, energy intake and average daily weight gain. The difference in the effect of the two restrictive feeding treatments on the digestibility of the ad libitum S2 ration gradually decreased over time, indicative of a recovery adaptation during ad libitum feeding period. The rate of DMD recovery post-realimentation was greater in the S1 sheep, likely due to their significantly lower DMD values immediately following underfeeding. We concluded that the comparatively higher nutritive value of the S2 ration sustained rumen digestive function throughout the restrictive feeding period, permitting sheep to commence re-feeding under conditions that are more favourable. Additionally, it is evident that reliance on livestock winter rations typical in western China, as expressed by the S1 ration, degraded ruminant digestive conditions to such an extent that feed was used with reduced efficiency even after being supplied in adequate quantities.

Effect of concentrate supplementation on nutrient digestibility and growth of Brahman crossbred cattle fed a basal diet of grass and rice straw.

BackgroundAn experiment was conducted in Vietnam to test the hypothesis that total dry matter (DM) intake and liveweight (LW) gain would increase in a curvilinear manner with increasing amounts of concentrate offered.MethodThere were five treatments: a basal diet of Guinea grass fed at 1 % of LW and rice straw fed ad libitum (T0), or this diet supplemented with concentrate at 0.6 (T1), 1.2 (T2), 1.8 (T3), or 2.4 % of LW (T4). The concentrate comprised locally available ingredients, namely cassava chips, rice bran, crushed rice grain, fishmeal, salt, and urea, mixed manually.ResultsConcentrate intake increased from T0 to T3, but there was no difference in concentrate intake between T3 and T4. Total feed intake increased in a curvilinear manner from 4.0 to 6.4 kg DM/d as the quantity of concentrate consumed increased. The substitution of concentrate for grass and rice straw increased with increasing consumption of concentrate and was as high as 0.49 kg DM reduction per kg of concentrate consumed. LW gain increased curvilinearly, with significant differences between T0 (0.092 kg/d), T1 (0.58 kg/d) and T2 (0.79 kg/d); but there were no significant differences in LW gain between T2, T3 (0.83 kg/d) and T4 (0.94 kg/d).With increasing amount of concentrate in the diet, the digestibilities of dry matter, organic matter, crude protein, and crude fat increased, but NDF digestibility decreased.ConclusionBased on these results, young Vietnamese Brahman-cross growing cattle will respond to a locally-sourced concentrate mix offered at a level of up to 1.2 % of LW.

Effect on performance of weanling alpacas following treatments against gastro-intestinal parasites

Nematodes and coccidia are common parasites of alpacas (Vicugna pacos), and important causes of disease in this increasingly popular livestock species. Endoparasitic infestation is thought to increase at times of natural or imposed stress, and antiparasitic treatments are often administered, although to date there is little evidence regarding their effect. Thirty-one alpaca juvenilles (cria) were divided into four groups at weaning, and received either no treatment as a control (C), fenbendazole anthelmintic (FB), toltrazuril coccidiostat (T), or both treatments (FBT). Body weights and faecal egg/oocyst counts were recorded weekly for six weeks following treatment. Although the prophylactic treatments decreased faecal egg/oocyst counts of the target organisms in the short term, there was no significant difference in egg/oocyst output over the course of the trial from animals given wormer, coccidiostat or both treatments. The group receiving anthelmintic only showed a significant reduction in live weight gain (LWG), with no significant difference in LWG between the other groups. At the conclusion of the trial, ‘wormed only’ alpacas weighed 3.3% less than at weaning, losing an average 1.3kg over six weeks, whereas average LWG in the control group was 2.5kg. Antiparasitics transiently reduced egg/oocyst output but results suggest that further investigation is required on the action of anthelmintics administered to alpaca cria at weaning and their effect on animal health and welfare.

The production cost of anthelmintic resistance in lambs

The economic impact of anthelmintic resistance was investigated in lambs by comparing productivity parameters in groups of animals treated either with a highly effective anthelmintic, or an anthelmintic to which three species of resistant worms were known to be present. Ten farmlets, each stocked with 30 lambs, were rotationally grazed for 5 months, with monthly treatments of either albendazole, to which resistance existed, or a new combination product containing derquantel and abamectin (DQL–ABA) to which there was no resistance. Stock on five farmlets were treated with each anthelmintic and productivity measures, including liveweights, body condition and faecal soiling were assessed throughout. In addition, fleece weights and information on carcass weight and quality was collected at the end of the trial.Anthelmintic efficacy was measured at the last two treatment dates by faecal egg count reduction test with larval cultures. Albendazole demonstrated efficacies of 48.4% and 40.9% for Trichostrongylus spp. and Teladorsagia circumcincta respectively. By contrast, the DQL–ABA treatments were >99% effective against all genera. The difference in live-weight gain was 9kg in favour of the DQL–ABA treatments. This translated into a 4.7kg increase in carcass weight with a 10.4% increase in carcass value. Significant differences in body condition scores, faecal breech soiling and fleece weights were also recorded, all in favour of the DQL–ABA treatments. The time required for 50% of the animals to reach a target live-weight of 38kg was significantly shorter (by 17 days) in those animals treated with DQL–ABA.The results show that the production cost of subclinical parasitism as a result of using an anthelmintic product which is less than fully effective due to resistance can greatly exceed the cost of routine testing of anthelmintic efficacy and the adoption of new anthelmintic classes. There is a strong case for many farmers to re-evaluate their position on some of these issues in order to optimise financial performance.

No loss of production due to larval challenge in sheep given continuous anthelmintic treatment via a controlled release capsule

This study aimed to quantify production loss due to larval challenge in sheep administered a controlled release albendazole capsule (CRC) and thus determine the suitability of CRC treated sheep as a proxy for worm-free sheep in grazing experiments.The experiment used an incomplete 2×3 latin square design with 81 Merino wethers. Sheep were either infected (INF) with mixed oral infection of albendazole-susceptible Haemonchus contortus, Trichostrongylus colubriformis, and Teladorsagia circumcincta (initial bolus then thrice weekly maintenance) or remained uninfected (UINF). Worm control treatments were with a CRC (CRCT), threshold treatment with a short-acting anthelmintic when worm egg count (WEC) exceeded 1500epg (TT) or untreated (UT). The experiment was conducted in two 63-day periods (separated by a 14 day washout period) with infection treatments swapped between periods. A subset of animals was killed at the end of each period for worm counts and tissue sampling.Faecal worm egg count in UINF-UT reached 10,204 and 6078epg at day 63 in periods 1 and 2, respectively, and remained 0 throughout in the CRT treatments. There was no difference in live weight gain or wool growth of INF-CRCT sheep (67 and 70g/d) relative to UINF-CRCT (67 and 76g/d). Live weight gain was significantly lower in INF-UT (27g/d) and INF-TT (55g/d) than UINF-UT (88g/d) or UINF-TT (81g/d) treatments. During the first infection period, greasy fleece weight growth was significantly lower in INF-UT (6.33g/d) and INF-TT (6.37g/d) than UINF-UT (7.80g/d) or UINF-TT (7.32g/d) treatments. The effects of infection on production persisted in INF-UT, but not INF-TT sheep for several weeks after termination of infection. Eosinophil counts were elevated in all infected groups and the antibody response to T. colubriformis was greater in INF-CRCT and INF-TT groups compared to uninfected sheep.Together, these results indicate that larval challenge in sheep with a CRC is mildly immunogenic but is not associated with production loss. The results also showed that the CRC itself reduced live weight gain and that anthelmintic treatment at a WEC threshold of 1500epg reduces production loss during infections and prevents persistence of adverse effects following infection.

Effect of using cassava products to vary the level of energy and protein in the diet on growth and digestibility in cattle

The effects of feeding different levels of energy and protein using cassava products ( Manihot esculenta Crantz) (roots and foliage) in the diet on growth rate and diet digestibility were studied in two experiments with growing cattle. In the growth trial, twenty-eight animals were allocated to a completely randomized 2 × 2 factorial design with seven animals per diet. The four diets consisted of two levels of crude protein (CP) (400 g and 540 g day − 1 ) and two levels of metabolisable energy (ME) (25 MJ and 32 MJ day − 1 ). The diets were formulated based on the nutrient content of cassava foliage, cassava roots, urea and elephant grass. The amount of urea was the same in all diets, 63 g head − 1 day − 1 , on DM basis. The digestibility trial was conducted after two months of the growth experiment. The lowest values of OM and GE digestibility were in the group fed the high CP and low ME level, while the group fed the low CP and high ME level had the lowest CP digestibility. There was a significant linear regression between OM digestibility and HCN intake and tannin intake in the groups fed on the low energy level. There was no significant difference in live weight gain between the groups fed either low ME, or high ME and low CP. The highest nutrient digestibilities were found in the group fed both high CP and ME resulting in a significantly higher daily gain, 558 g day − 1 . In conclusion, an increased level of CP and ME in the diet, achieved using cassava products, improved diet digestibility and growth rate of cattle fed low quality grasses. In order to overcome the negative effect of HCN, cattle fed high amounts of cassava foliage should be supplied with extra energy in the diet.

Effects of including chicory in perennial ryegrass–white clover leys on production and health in organic lambs

Two trials were conducted to examine the effect of chicory included in or as additional plots of the ryegrass–white clover pastures on growth, naturally acquired nematode infections and selectivity of chicory by lambs. In Experiment 1, 31 weaned Texel lambs (36 ± 7 kg) grazed either ryegrass–white clover (CTRL) or ryegrass–white clover–chicory pastures (CHIC). In Experiment 2, 30 weaned Shropshire lambs (32 ± 7 kg) grazed either ryegrass–white clover (CTRL) or ryegrass–white clover with access to small additional chicory plots, which corresponded to 3% (CHIC-LO) or 6% of the total grazing area (CHIC-HI). No consistent differences in live weight gain and nematode faecal egg counts were observed in lambs grazing the different pasture types. Sward height on the ryegrass–white clover–chicory pasture was higher than the ryegrass–white clover pasture in the period from the 21th August to October in Exp. 1 and in the period from July to mid August in Exp. 2. In Exp. 1 ewe lambs in CHIC performed better than ram lambs (197 ± 11 vs. 154 ± 13 g day − 1 ; P < 0.05 for ewe vs. ram lambs) whereas ram lambs performed best without chicory (190 ± 13 vs. 177 ± 11; P < 0.05 for ram vs. ewe lambs). The relative proportion of chicory eaten by lambs did not differ significantly from August to October and averaged 4.0%. Lambs showed a consistent aversion to chicory. It can be concluded that including chicory into a well-managed mixed sward of perennial ryegrass and white clover 1) improved herbage availability under conditions that are suboptimal for ryegrass/clover swards but 2) did not give consistent effects on growth performance or reduction of nematode infection levels of grazing lambs probably due to a low intake of chicory, as lambs avoided chicory in a mixed sward of high quality. The negative selection of chicory by lambs makes a strategic utilization of chicory's potential in a mixed sward difficult under relatively fertile soil conditions.

Vitamin B12 absorption and metabolism in milk-fed lambs

AIM: To quantify aspects of absorption and retention of vitamin B12 from milk in pre-ruminant lambs, and the possible effect of activation of dependent metabolic pathways (propionatesuccinate) on vitamin B12 concentrations in tissues. METHODS: In Experiment 1, two groups of eight newborn lambs each received either milk substitute alone, or milk substitute with added propionate for 4 weeks. Half of the lambs in each group received vitamin B12 injections twice weekly. Blood and liver samples were taken on Day —1 and at the end of the trial, and blood was also collected twice weekly, for measurement in plasma of vitamin B12, methylmalonic acid (MMA), and blood-binder transcobalamin II/haptocorrin. The lambs were weighed at 0, 2 and 4 weeks. In Experiment 2, 12 milk-fed newborn lambs (n=2 or 3/group) were injected I/M with 0.2, 0.4, 0.8, 1.6 or 3.2 µg vitamin B12 and a further 12 were supplemented orally with 2, 4, 8, 16 or 32 µg vitamin B12, daily for 2 weeks. Three lambs remained as untreated controls. Blood and liver samples were taken at the start and end of the trial, and blood was also collected twice weekly, for measurement of vitamin B12 and MMA concentrations in plasma. The lambs were weighed on Days 0, 7 and 14. In Experiment 3, 14 lambs from Experiment 2 were used to repeat the highest I/M and oral rates of supplementation used in Experiment 2. Blood samples were taken at frequent intervals for 24 hours, and analysed for concentrations of vitamin B12 in plasma. RESULTS: Propionate supplementation was associated with increased concentrations of vitamin B12 in plasma in lambs supplemented with vitamin B12 but not in those not supplemented (p=0.047), but had no detectable effect on concentrations of vitamin B12 in liver (Experiment 1). Lambs with concentrations of vitamin B12 in plasma and liver in the marginal reference range were able to metabolise propionate and maintain normal concentrations of MMA at a rate of intake of propionate close to that which would depress appetite. Close to 100% of the vitamin B12 administered by I/M injection appeared in plasma in the first hour but 85% was removed from the circulation within 16 hours. The maximum liver concentration was achieved at 900 nmol/kg (=1,200 µg) fresh tissue. There were no significant differences in liveweight gain (LWG) regardless of treatment. CONCLUSIONS: Lambs with concentrations of vitamin B12 in plasma and liver in the marginal reference range were able to metabolise propionate and maintain normal concentrations of MMA in plasma at a rate of absorption of propionate close to that which would depress appetite. The coefficient of absorption of oral vitamin B12 in milk-fed lambs was low (<10%), and the ability of lambs to retain the vitamin even when tissues had physiologically low concentrations was poor. CLINICAL RELEVANCE: Pre-ruminant lambs had a low requirement for vitamin B12, and even at low tissue concentrations had poor ability to absorb and retain the vitamin. However, if supplementation is required, a method that provides a modest but continual supply may be most effective in protection against deficiency.

A bromochloromethane formulation reduces enteric methanogenesis in cattle fed grain-based diets

Enteric fermentation has been estimated to be responsible for 64.2 Mt CO2-e, or ~16% of Australia’s greenhouse gas emissions (Australian Greenhouse Office 2007). A bromochloromethane (BCM) formulation, previously shown to inhibit methanogenesis, was included in the diet of Brahman (Bos indicus) cross steers, twice daily in three separate experiments, to determine the effect on methane production, daily feed intake, liveweight (LW) gain and accumulation of residues of BCM in edible tissue. In the first experiment, the BCM formulation was fed at rates of 0, 0.15, 0.30, or 0.60 g/100 kg LW, twice daily, for 28 days. Methane production (mean ± s.e.), measured over 11 h after feed was first consumed on day 28, was 0.3 ± 0.13 and 0.1 ± 0.03 L/h for animals treated at a rate of 0.30 and 0.60 g/100 kg LW, respectively. This was significantly less (P &lt; 0.05) than for control animals (4.6 ± 0.46 L/h) and animals treated at a rate of 0.15 g/100 kg LW (2.1 ± 0.28 L/h). The dose rate of 0.30 g/100 kg LW was associated with a decrease in methanogenesis by ~93% compared with the control group and was used in subsequent experiments. The second experiment evaluated the efficacy of the BCM formulation fed at rates of 0 or 0.30 g/100 kg LW, twice daily, for 90 days. Methane production was measured over 24-h periods, on days 30, 60 and 90. For days 30 and 90, methane production was reduced by 60% (P &lt; 0.05) to 4.2 ± 1.82 L/h and by 50% (P &lt; 0.05) to 6.1 ± 0.63 L/h, respectively, for treated animals compared with the control group. The final experiment determined the effect on LW gain and detectable residues in edible tissue, with animals given the BCM formulation at rates of 0 or 0.30 g/100 kg LW, twice daily, for 85 days. Liver, kidney, depot fat and muscle samples collected 1 and 10 days after the last day of treatment had concentrations of BCM that did not exceed 0.015 mg/kg and were less than the temporary maximum residue limit (0.02 mg/kg BCM), which applies to bovine meat, fat and edible offal. There were no significant differences in LW gain (1.4 ± 0.10 v. 1.5 ± 0.07 kg/day), feed conversion ratio (5.7 ± 0.32 v. 5.4 ± 0.09), hot carcass weight (235 ± 5.0 v. 250 ± 6.5 kg) or P8 fat depth (6.4 ± 0.89 v. 8.1 ± 1.15 mm) between control and treated animals. The experiments reported here were completed in 2004 before the Australian Government prohibited the manufacture and use of BCM. It is unlikely that the BCM formulation will be available for commercial use to mitigate livestock methane emissions in Australia. Nevertheless, the study has demonstrated that methane emissions were substantially reduced over a 90-day feedlot finishing period. This indicates that alternative antimethanogens with a similar mechanism of action may have practical commercial relevance.

Effects of feeding level and protein content of milk replacer on the performance of dairy herd replacements

It has been suggested that United Kingdom recommendations for feeding the neonatal calf (∼500 g milk replacer (MR)/day; ∼200–230 g CP/kg milk powder) are inadequate to sustain optimal growth rates in early life. The current study was undertaken with 153 high genetic merit, male and female Holstein-Friesian calves (PIN2000 = £48) born between September and March, with heifers reared and bred to calve at 24 months of age. Calves were allocated to one of four pre-weaning dietary treatments arranged in a 2 MR feeding level (5 v. 10 l/day) × 2 MR protein content (210 v. 270 g CP/kg dry matter (DM)) factorial design. MR was reconstituted at a rate of 120 g/l of water, throughout, and was offered via computerised automated milk feeders. Calves were introduced to pre-weaning diets at 5 days of age and weaned at day 56. During the first 56 days of life, calves offered 10 l MR/day had significantly higher liveweight gains (P < 0.001) than calves fed 5 l MR/day. No significant differences in liveweight gain were found between calves fed 210 g CP/kg DM MR and those fed 270 g CP/kg DM MR from birth to day 56. Differences in live weight and body size due to feeding level disappeared by day 90. Neither MR feeding level nor MR CP content affected age at first service or age at successful service, and with no milk production effects, the results indicate no post-weaning benefits of increased nutrition during the milk-feeding period in dairy heifers.

Effect of muddy conditions in the field on the liveweight gain of cattle consuming Leucaena leucocephala - Digitaria eriantha pastures in north-west Australia

Cattle grazing leucaena (Leucaena leucocephala cv. Cunningham)–pangola grass (Digitaria eriantha cv. Steudel) pastures in the Ord River Irrigation Area in north-west Western Australia, sometimes exhibit higher liveweight gains in the dry season when temperature and humidity are lower. Two factors have been suggested as causing this seasonal difference: the combined effect of the temperature and humidity, and the effect of the muddy conditions in the field associated with rainfall in the wet summer season. An experiment over 81 days, from August to October 1995, was conducted to evaluate the effect of muddy conditions on the liveweight gain of cattle grazing a leucaena–pangola grass pasture. Replicated paddocks were grazed in a normal irrigated system during this dry season whereas other paddocks were flood irrigated twice weekly to create muddy conditions. Cattle grazing the muddy paddocks had a liveweight gain of 0.29 kg/steer.day, which was lower (P &lt; 0.001) than the animals in the dry paddocks (0.57 kg/steer.day). These cattle spent less time grazing (41.9 v. 67.6% of animals grazing at three observation times, 0600, 1100 and 1500 hours, on each day over the whole 81 days; P ≤ 0.001). It was suggested that the muddy condition of the paddock was the primary factor causing this difference in liveweight gain and grazing behaviour.