Animal Production Science
Volume 54 Number 10 2014
Harnessing the Ecology and Physiology of Herbivores
The control of energy intake includes mechanisms that act independently, as well as interacting factors that likely affect feeding via their effects on hepatic oxidation. Mechanisms controlling energy intake and partitioning are entwined and inseparable and are affected by type and availability of fuels determined by diet and physiological state. The conceptual model presented in this article might help improve our understanding of control of feeding in ruminant animals.
AN14334Antioxidant dynamics in the live animal and implications for ruminant health and product (meat/milk) quality: role of vitamin E and selenium
Antioxidant dynamics in live animal has implications on ruminant health and product quality. This review article presents the recent developments in understanding the changing dynamics of vitamin E and selenium and their role to improve ruminant production under various metabolic and environmental challenges.The evidence suggest that their role extend beyond the antioxidant functions, when given on higher levels than recommended.
AN14210Win–win strategies for high beef quality, consumer satisfaction, and farm efficiency, low environmental impacts and improved animal welfare
A relevant combination of indicators related to intrinsic and extrinsic quality traits in a prediction model will achieve a global evaluation of overall beef quality. It may also identify win–win strategies between sensory and nutritional quality, farm economic efficiency and social and environmental considerations (such as e.g. carbon footprint, animal welfare, grassland biodiversity, rural development).
AN14555Recent developments in lipid metabolism in ruminants – the role of fat in maintaining animal health and performance
The article reviews the current knowledge regarding associations between ruminant lipid metabolism and economically relevant animal health/performance traits. Established concepts to tailor animal lipid metabolism are summarised, and novel analytical/experimental strategies are highlighted that expand traditional application-oriented approaches via improved analysis tools, omics-approaches, cell model systems and systems biology methods.
Accurate characterisation of responses to specific stressors encountered by production animals requires an analysis of key indicators of endocrine, immune and cellular adjustments as the animal strives to sustain homeostasis. Acute phase proteins can provide an important initial indication of the nature of a stressor; when combined with cytokine and cellular immune analyses, the severity of the consequences of a specific stress can be diagnosed. Responses to physical, infectious, metabolic and psychological stressors encountered by calves during their development have been reviewed herein. No single class of molecules or cells has been identified as a definitive diagnostic for any of these stressors, but rather a multi-factorial analysis is required.
AN14377A need for generating sound quantitative data at national levels for feed-efficient animal production
For enhancing efficiency of feed utilisation at a national level it is imperative to estimate feed resource availability, assess the manner of their utilisation, and generate reliable data on their chemical composition and nutritional value. Approaches and methodologies for achieving these objectives are discussed. Generation of sound data on feed resources is vital for feed-efficient sustainable livestock production.
Glycogen metabolism has commercial relevance within ruminant production systems given its link to dark cutting and other physiological disorders. This paper contrasts ruminant glycogen metabolism in liver and muscle to that of simple stomached species, highlighting differences in their tissue prioritisation for glycogen storage during the post-prandial/post-exercise state. We also demonstrate recent advances in understanding the impacts of genotype, age, and temperament.
AN14607Livestock water productivity: feed resourcing, feeding and coupled feed-water resource data bases
On a daily basis, about 100 times more water is required for livestock feed production than for drinking water. Water requirement for feed production can be reduced four-fold by choosing agricultural byproducts, breeding water-use efficient crops and forages and by closing yield gasp in crop and livestock production. Since feed production results in substantial demand for water it should be linked with water demand estimates.
AN14274NutriPhysioGenomics applications to identify adaptations of cattle to consumption of ergot alkaloids and inorganic versus organic forms of selenium: altered nutritional, physiological and health states?
Two prevalent health challenges of forage-based beef cattle production in south-eastern USA are fescue toxicosis and selenium (Se) deficiency. Using a combination of nutriphysiogenomic and targeted gene approaches our research has characterized tissue-level genomic and protein changes in response to these physiological challenges. Consequently, potential biochemical targets for amelioration by nutritional regimens have been identified.
AN14279Effects of cloprostenol and flurogestone acetate sponge on embryo yields and quality in indigenous ewes in Bangladesh
The effects of two doses of cloprostenol and two doses of flurogestone acetate sponge on the onset of oestrus, and embryo recovery and quality in indigenous ewes in Bangladesh were evaluated. The best synchronisation protocol for the recovery of acceptable numbers of normal embryos was a combination of 45 mg FGA with 600 IU PMSG.
The study was conducted to evaluate the performance of the Wood model to describe the characteristics of lactation curves of dairy ewes under organic management. The Wood model detected that 52.06% of lactation curves had a continuously decreasing shape (atypical curves). A reasonable fit of lactation curve was showed by Wood model, but presented deficiencies of fit in atypical curves.
The live weight gain (LWG) of male Bali cattle (Bos javanicus) remained relatively constant at ~0.4 kg/day from 12 to 27 months of age, whereas there was a sharp decrease in LWG of females after 18 months of age compared with LWG from 6 to 18 months of age. This demonstrates the sexually dimorphic control of post-pubertal growth in Bali cattle.
Smallholder large ruminant improvement requires farmer engagement that promotes the value of knowledge and intervention adoption. Growing introduced forages facilitated farmer engagement in southern Cambodia, expanding from 52 to 1306 plots in 4 years. Forage quality at 30 days post first harvest was comparable to published values, improving average daily liveweight gain of cattle and saving farmers up to 2 h labour per day.
AN14251Modelling the effect on stocking rate and lamb production of allowing ewes to graze a dual-purpose wheat crop in southern New South Wales
Grazing dual-purpose wheat provides high quality feed for livestock at a time of year when pasture growth rates in southern Australia may be slow, and farmers may therefore consider changing their time of lambing to exploit this. Simulation modelling of a Merino ewe flock producing first-cross lambs and grazing lucerne-based pastures identified that the optimal time of lambing, in terms of highest median gross margin over the long-term, was not changed by inclusion of crop grazing in winter. Allowing ewes to graze a wheat crop in winter increased producer returns and reduced supplementary feeding requirements and the variability of returns.
AN14435Using partial records to identify productive older ewes to retain in the breeding flock to increase the flock net reproduction rate
Identifying and retaining older ewes with high lifetime reproductive performance can increase flock productivity and profitability. However, collecting data on lifetime reproductive performance is difficult. This study has shown that pregnancy scanning information at 2 and 3 years of age combined with udder examination at marking can identify ewes likely to have high lifetime reproductive performance.
AN14195Limited application of irrigation water does not affect the nutritive characteristics of lucerne
A large-scale field experiment was conducted to determine the effect of limiting and non-limiting irrigation treatments on the dry matter production and nutritive characteristics of lucerne. Dry matter production generally increased as the total water supply increased; however, neither mean dry matter digestibility concentration nor mean crude protein concentration were affected by irrigation treatment. There was no consistent effect of restricted irrigation on the neutral detergent fibre concentration of the lucerne plants.
AN14214Effects of crossbreeding on milk production and composition in dairy sheep under organic management
Crossbreeding of local sheep breeds with dairy breeds is an option to improve dairy production parameters. We evaluate the effect of crossing local sheep breeds with a specialised dairy sheep breed (East Friesian) on milk production chemical composition and characteristics of the lactation curve. East Friesian × Suffolk is an option of crossbreeding in dairy sheep systems under organic management.
Chicory, a summer-active forage crop, is an alternative herbage source to perennial ryegrass for dairy cows in southern Australia. However, there is limited understanding of nutrient selection from chicory by grazing dairy cows. Nutrient selection, the difference between nutrients in herbage offered and consumed, was measured in chicory during spring 2012. Preferential grazing for leaf rather than stem from chicory may affect nutrient selection in a way that differs from perennial grass species.
AN14171Nitrogen partitioning, energy use efficiency and isotopic fractionation measurements from cows differing in genetic merit fed low-quality pasture in late lactation
No information is available regarding nitrogen and energy use efficiency in relation to nitrogen isotopic fractionation measured from cows with different genetic merit. Eight high and eight low breeding worth cows were used to conduct a nitrogen balance study, and the results showed nitrogen isotopic fractionation and breeding worth were useful indicators of dry matter intake and nitrogen use efficiency of individual cows, respectively. Both indicators are easy to obtain on farm and could be further developed for dairy cow breeding programmes.
AN14163Effect of feeding a balanced ration on milk production, microbial nitrogen supply and methane emissions in field animals
Dairy farmers in developing countries should be aware of the benefits of balanced feeding to their milch animals. Application of balanced nutrition approach, using locally available feed resources and area-specific mineral mixtures, in small-holder dairy systems of India improved nutrient utilisation, milk production, microbial nitrogen supply, and reduced methane emissions in field animals.
AN14378Ruminal inoculum activity in cattle supplemented with corn grain at different daily frequencies: evaluation using the in vitro gas-production technique
This study evaluated rumen fermentation activity of heifers fed pasture supplemented with corn at different daily frequencies. Increasing supplementation frequency did not show benefits, at least with this type of pasture (9% of crude protein, 60% of neutral detergent fiber) at this supplementation rate (1% BW) with corn.
AN14422Effects of site of assessment and variation in wool quality traits on the tactile assessment of textural greasy wool handle
Textural greasy wool handle varies across the fleece. This study quantifies the variation that is observed when assessing textural greasy wool handle and highlights the importance of selecting a common site for the assessment of textural greasy wool handle.
AN14302Pattern of partitioning of aflatoxins from feed to urine and its effect on serum chemistry in Nili-Ravi buffalo heifers
Pakistan is the second largest producer of buffalo milk (22.96 million tonnes) and meat (0.775 million tonnes) in the world, with production worth US$8.698 and 2.087 billion, respectively. The concentrate feed base available to these animals is often contaminated with fungal mycotoxins, which when ingested alter the animal’s metabolism, health status and reproductive potential. Changes in serum chemistry and urinary output as a measure of metabolic adjustment are detailed in this study.
AN14221A pilot study into the use of global navigation satellite system technology to quantify the behavioural responses of sheep during simulated dog predation events
With welfare concerns and questions over the sustainability of the Australian sheep industry in some regions due to the devastating effects of dog attacks, new innovative technologies are being investigated to manage this issue. The aim of this study was to determine if the behaviour and speed of movement of sheep changed following an attack. Sheep exhibited higher speeds of movement in conjunction with a variety of behavioural changes during this event, highlighting the potential use of remote sensing technologies to alert producers of a predation event.
Chemical and biological additives should be used to improve the quality of sugarcane silages. We evaluated some additives and our study showed that applying 1.0 kg of quicklime to each 100 kg of sugarcane improves the nutritional characteristics of sugarcane silage SP81-3250. This study may help farmers and feedlots to optimise the use of this roughage.
Remote monitoring can enable precise management of livestock production systems to improve productivity and sustainability. The aim of this study was to explore the value of frequently collected live weight, and animal location and behaviour. These new technologies captured changes in live weight and performance, and landscape utilisation by animals reflecting the effects of environmental and management factors in near real-time.
The month of joining and lamb sale strategy have the potential to impact on the profitability of lamb production. Simulation modelling showed that differences in gross margins between lamb sale strategies were small if the optimum stocking rate for month of joining was used, but a flexible sale policy used the least feed resources. The results suggest the most advantageous lamb sale strategy varies with both the month of joining and stocking rate used.
AN14233Effects of calcium salts of medium-chain fatty acids on plasma metabolite and hormone concentrations in early lactating dairy cows
In dairy cows, medium-chain fatty acids (MCFA) can be used as an energy source, while their calcium salts (MCFA-Ca) increase plasma ghrelin levels, stimulating the appetite of animals. We investigated the effects of MCFA-Ca on milk production, plasma metabolite levels and hormone concentrations in early lactating dairy cows. MCFA-Ca supplementation did not affect feed intake or milk production, but influenced plasma metabolite and hormone concentrations. Our results suggest that MCFA-Ca supplementation in early lactating cows may result in enhanced catabolism, mediated by changes in the endocrine system and nutrient metabolism.
AN14141The effect of silage plant species, concentrate proportion and sugar beet pulp supplementation on the performance of growing and finishing crossbred bulls
The present study examined the effects of silage plant species, concentrate proportion and sugar beet pulp supplementation on the performance of growing and finishing crossbred bulls. Bulls fed either pure timothy grass or mixed timothy grass and red clover silages performed similarly. Molassed sugar beet pulp is a suitable energy supplement for bulls when feeding barley grain and silage-based diets.
AN14258Effect of type and inclusion level of cold-pressed oilseed cakes on in vitro rumen fermentation
The high lipid content of cold-pressed oilseed cakes (CPOC) make them an effective energetic feed stuffs for beef cattle, but may also alter the rumen fermentation if the type and level inclusion of CPOC are not adequately chosen. This study evaluated the effects of different type and level inclusion of CPOC on in vitro rumen fermentation. No effect has been observed when either palm fat or cold-pressed rapeseed cake were added but cold-pressed sunflower cake altered microbial fermentation at a total fat level of 60 g/kg of dry matter.
AN14058Ensiling characteristics of rice whole stillage inoculated with or without Amylomyces rouxii and evaluation of the feeding value for growing Japanese black steers
Rice whole stillage (RWS) is disposed to aerobic spoilage when stored for a prolonged period. The objectives of this study were to evaluate the fermentation characteristics of ensiled RWS and their feeding impact on Japanese black steers. Results revealed that RWS can be stored by ensiling for a prolonged period without spoilage, and was successfully used for feeding steers. Collectively, ensiling RWS provides a promising nutritional feedstuff for beef producers.
The Australian sheep industry is concerned about lamb mortality. GPS collars were placed on pregnant ewes to test if changes in pre-lambing behaviour could be used to identify lambing. The mean daily and hourly speeds and mean distance from peers were calculated. From these metrics only the day of lambing, not the actual time, could be identified.
Isotopic dilution methodology of [U-13C]glucose and [1-13C]Na-acetate were performed simultaneously as primed continuous infusions to determine plasma glucose and acetate metabolism in sheep during thermoneutral and cold exposure (CE, 2–4°C). The present findings suggested that plasma acetate turnover rate tended to be elevated during CE, with further, more extensive, studies required to clarify the significance.
This study was designed to address the GLP-1 and ghrelin-induced metabolic changes in the liver of steers using a metabolomics approach. Metabolomics analysis showed that GLP-1 is involved in glycolysis/gluconeogesis, lipogenesis and lipid export from the liver, oxidative stress defense and protein turnover pathways. Ghrelin was shown to be involved in pathways related to glycolysis, protein anabolism and phospholipid biosynthesis.
Short-term methane emission measurements were adequate to show dietary nitrate tended to reduce emission and change the feeding pattern of feedlot cattle. The significant diet effect on the interval between feed consumption and methane measurement may have confounded the ability of short-term methane measurements to provide data suitable for accurately estimating methane per unit feed intake. Caution is needed in extrapolating short-term emission measures into daily emission rates when evaluating quick-acting rumen modifiers.
AN14229Grazing alternative herbages in lactation increases the liveweight of both ewe lambs and their progeny at weaning
These studies were designed to determine the impact of offering pregnant ewe lambs either lucerne or a herb mix containing chicory, plantain and red clover and white clover in late pregnancy and lactation. It was found that these alternative herbages increased both the liveweight of the young dam and her progeny at weaning in comparison to a ryegrass and white clover sward.
AN14342Estimation of dry matter intake by n-alkanes in dairy cows fed TMR: effect of dosing technique and faecal collection time
To select dairy cows according to efficiency of milk production it would be beneficial to estimate individual intakes, which can be predicted using n-alkanes as inert markers. A simplified procedure based on once-daily dosing of C32 alkane and spot sampling of faeces was tested. Dosing the marker in a top-fed concentrate and collecting faeces at morning feeding time represents a valuable protocol to accurately estimate individual feed intake on a large number of animals.
AN14361Meal pattern analysis for effects of compound feed formulation in mid to late lactating dairy cows fed hay and compound feed both ad libitum
Meal pattern analysis was conducted to determine the effect of compound feed formulation on feed intake behavior of dairy cows with ad libitum access to compound feeds and forage. Twenty Holstein-Friesian lactation dairy cows received grass hay and one of two compound feeds, contrasting in neutral detergent fibre and starch content. Neither feed intake nor intake behavior were affected by compound feed formulation.
AN14292Methane emissions of dairy cows cannot be predicted by the concentrations of C8:0 and total C18 fatty acids in milk
Methane emissions from ruminants are difficult and expensive to measure. We investigated whether we could predict methane emissions from dairy cows from the concentrations of C8:0 or total C18 fatty acids in milk because of evidence for this in the literature. It was concluded that methane emissions cannot be accurately predicted based solely on the concentrations of these fatty acids in milk.
Data were obtained from 209 progeny generated using an unbalanced nested design, with three does mated to each of six bucks to estimate genetic parameters for litter traits of grasscutters. Heritability values of 0.56 ± 0.21 and 0.22 ± 0.22 were obtained for litter weight at birth from dam component and both sire and dam components, respectively. For litter weight at weaning, h2 estimate was 0.66 ± 0.22 using the dam component of variance. Genetic correlation between litter weight at birth and litter weight at weaning was 0.59, revealing a positive relationship between both traits.
AN14356The incidence of dark cutting in southern Australian beef production systems fluctuates between months
Dark cutting reduces beef quality significantly and is a financial burden on the industry. The incidence of dark cutting is affected by glycogen concentration and therefore pasture quality. This study has identified that in southern Australia, the risk of dark cutting is highest in late summer through to early winter.
AN14366Influence of supplementation of tropical plant feed additives on in vitro rumen fermentation and methanogenesis
Suitable strategies and policies are needed to curtail the rumen methane emission that contributes substantially to global warming. On screening some tropical plants, Psidium guajava leaves were found to decrease rumen methane production without affecting nutrient degradability in vitro. These leaves have a potential to be used as feed additive for sustainable eco-friendly livestock production.
AN14289Nutritional characteristics and in vitro digestibility by near-infrared spectroscopy of local and hybrid napiergrass varieties grown in rain-fed and irrigated conditions
Napiergrass yield large biomass and have positive impact on animal production but its productivity in limited by drought stress. Hybrid napiergrasses were developed and some of those were found to be reasonably high in nutrient profile and well digestible when characterised by NIRS, even in low irrigation/rain-fed condition. Thus, some hybrid napiergrasses can be grown in rain-fed farming condition.
AN14262Effect of temperature and pre-incubation time of fibrolytic enzymes on in vitro degradability of Brachiaria (Brachiaria decumbens)
Ruminant production in Brazil is based on grazing that provides forage for ~250 million cattle. Use of exogenous fibrolytic enzymes has shown increases in forage utilisation and efficiency of ruminants. Our findings highlight that Brachiaria grass may respond well to exogenous application of cellulase at all environmental conditions studied. Enhancement on forage utilisation may improve the efficiency to convert grass to meat.
Regulations often require night-time lighting in dairy barns but night-lights may interfere with cows’ rest. The aim was to test low night-light intensities on cow activity and milk production in automatic milking systems and it was shown that 11 lx can be used at night without reducing activity, but milk yield decreased 1 kg/day. Legislation requiring night-light supports productivity rather than animal welfare.
When ruminants belch, they release the greenhouse gas, methane into the atmosphere. Scientists are searching for ways to reduce ruminants’ contribution to greenhouse gases and our study aimed to provide a better understanding of methane formation in the rumen. Our results indicate that the accepted view that carbon dioxide in rumen fluid is the main carbon source for methane synthesis needs re-evaluation.
Organic farming is increasing over the world and it is necessary to produce animal feeds of high nutritive value. This study analysed forage yield and quality of several winter oatsâlegume intercrops and results showed that intercropping with bard vetch was the best alternative. These results should be confirmed in multi-year studies before drawing up guidelines for organic farmers.
Wireless sensor networks (WSN) offer novel methods for measuring livestock phenotypes in commercial grazing environments. We have established a program of research to measure intake, efficiency and behaviour of grazing livestock using WSN. This paper details the concepts, methods and technical challenges associated with establishing these WSN based methods, and some initial results from our program of research.
AN14168Identification of bioactive grassland plants for reducing enteric methane production and rumen proteolysis using an in vitro screening assay
A total of 156 plant species collected in French Massif Central were screened by measuring several parameters, including digestibility, methane production and ammonia using an in vitro rumen fermentation assay. We observed that the fermentation of several plants severely decreased methane per unit of organic matter truly digested and the ratio between ammonia and plant N content compared with perennial ryegrass.
AN14382Pasture intake and milk production of dairy cows grazing annual ryegrass with or without corn silage supplementation
Three supplementation levels of corn silage (0, 4 and 8 kg DM/day) were compared on a Latin square design with 9 dairy cows strip-grazing annual ryegrass at a medium pasture allowance (35 kg DM/cow). Pasture intake was similar for all treatments and total DM intake and milk production increased linearly with supplementation level.
Inclusion of olive cake in the diet of beef steers might reduce feeding costs without affecting animal performance. The present work was carried out to check for this hypothesis, and the results showed that inclusion of up to 20% second-extraction pitted and dehydrated olive cake in the diet did not affect performance of beef steers. Inclusion of those ingredients in the ration might be suitable depending on their market price.
AN14372Relationships of both urine nitrogen output and plasma urea concentration with rumen protein balance in lactating goats
In the updated INRA system, rumen protein balance (RPB) was proposed to better fit feed evaluation, animal requirements and responses to diets. This study tested the relationships between RPB and N urinary outputs or plasma urea concentration in a large data set obtained from lactating goats. Due to high correlations, RPB can be used to estimate the urinary nitrogen outputs.
AN14252Bioactive forage legumes as a strategy to improve silage quality and minimise nitrogenous losses
One key issue for livestock breeding systems to reach out towards sustainability is to use feeding resources satisfying both nutritional and environmental concerns. We focused on bioactive legumes and showed that their inclusion in grass silages improved their conservation and quality via lower protein degradation. This could reduce nitrogen losses with potential beneficial effects for both ruminants nitrogen efficiency and the environment.
AN14193Effects of different doses of sodium monensin on rumen papillae and tissue histology of feedlot Nellore cattle
This study aimed to test the potential as feed additive of a new formula of sodium monensin. Effects of doses of sodium monensin on rumen epithelium of feedlot cattle were studied, and doses of 9 or 36 ppm promoted better development of rumen epithelium. An alternative formula of sodium monensin at cheaper cost has the potential to be used as feed additive in diets for feedlot cattle.
AN14296Effect of supplementation with saponins from Yucca schidigera on ruminal methane production by Pelibuey sheep fed Pennisetum purpureum grass
Methane is the main greenhouse gas emitted by ruminants and could be reduced throughout the use of plant secondary metabolites. In this research, saponins from Yucca schidigera were supplemented to Pelibuey sheep fed tropical grass and the ruminal methane production was unaffected. This result was due to the lack of effect on intake and rumen fermentation in sheep under tropical conditions.
AN14332Effects of cooked molasses licking block supplementation pre- and post-partum on feed intake, suckling lamb performance, milk yield and milk quality in dairy sheep. Part 1
Nutrition during late pregnancy is crucial to optimise the performance of dairy sheep. Cooked molasses licking blocks were offered freely to dairy ewes from Day -60 to Day 60 after lambing resulting in trends to milder prepartum decrease of body condition score, heavier litter size and higher milk fat content than unsupplemented ewes. Results suggest an effect of block supplementation at the digestive and/or metabolic level.
AN14310The effect of maternal arginine supplementation on the development of the thermogenic program in the ovine fetus
The results provide new insights into the regulation of brown adipose tissue development in the ovine fetus and indicate that maternal arginine-supplementation during mid-to-late gestation may increase lamb survival through enhanced thermoregulatory ability. These findings highlight the potential of specific nutrient supplementation in early life to improve the welfare and economic outcomes of lamb production on NZ sheep farms.
AN14328New approach to improve the calibration of main fatty acids by near-infrared reflectance spectroscopy in ruminant meat
Determination of polyunsaturated fatty acids (PUFA) composition, which has a great nutritional interest in meat, is a great challenge for consumers and industry. Safe, environmentally, friendly and simple routine methods, like near-infrared reflectance spectroscopy (NIRS) are required. However, NIRS models for predicting PUFA of beef meat are not precise enough. Our study shows that models developed from beef + lamb meat spectra databases yielded more precise prediction of main fatty acids of meat than the models based only on the beef meat spectra database.
AN14315Factors influencing the occurrence of high ultimate pH in three muscles of lamb carcasses in Australia
Greening during meat storage is usually caused by high pH. The occurrence of high ultimate pH (pHu) in the rack, blade and knuckle cuts was investigated using 1614 lamb carcases. The pHu of the knuckle, rack and blade was 6.06, 5.79 and 6.12, respectively. Lighter carcass weights, Merinos, electrical stimulation and autumn (vs spring) increased the pHu in these muscles.
AN14329Use of nitrate and Propionibacterium acidipropionici to reduce methane emissions and increase wool growth of Merino sheep
Supplementing sheep with 2% dietary nitrate and Propionibacterium acidipropionici (PA) confirmed the beneficial effects of nitrate on net greenhouse gas reduction and wool growth. However, PA supplementation was not effective in reducing methaemoglobinaemia and it appears that methaemoglobinaemia risks may be higher when diets are fed at a restricted level and contain only low levels of readily fermented carbohydrate.
Brahman (BRAH) and F1 Senepol × Brahman (F1 SEN) steers were compared for growth grazing pasture in the NT, growth in a feedlot in Queensland, carcass characteristics and meat tenderness. On average growth was 10 kg higher in F1 SEN during grazing in the 9 months following weaning, there was no significant difference in feedlot growth, F1 SEN carcasses graded 2 boning groups lower in the Meat Standards Australia (MSA) grading system, and M. longissimus samples from F1 SEN were found to be significantly more tender than BRAH by shear force testing. These results indicate that crossbreeding with a tropically adapted Bos Taurus breed, such as the Senepol, may be a viable method for cattle producers with Brahman herds in northern Australia to improve the meat quality of the cattle they produce.
AN14394The effect of lipid sources on intake, rumen fermentation parameters and microbial protein synthesis in Nellore steers supplemented with glycerol
This study was to investigate the effect of glycerol and fat sources on Nellore steers. The combined use of this sources resulted in no changes in rumen pH, DM intake, microbial protein production, and acetate. The molar proportion for propionate increased. These results suggest that combined use of lipid with glycerol could be used in dietary strategies without adverse effects.
AN14311Thermoregulatory differences in lactating dairy cattle classed as efficient or inefficient based on residual feed intake
Understanding the physiological phenotype that underpins efficiency is important to facilitate improvements in production. This project examined measures of thermoregulation in dairy cattle classed as efficient or inefficient based on residual feed intake (RFI) and found inefficient cows tended to have higher skin temperatures than efficient cows. This study suggests that aspects of efficiency are attributed to differences in thermoregulation.