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Camden Haven, Australia

Bisinotto R.S.,University of Florida | Lean I.J.,SBScibus | Thatcher W.W.,University of Florida | Santos J.E.P.,University of Florida
Journal of Dairy Science

A systematic review of the literature was performed with the objective to evaluate the effects of progesterone supplementation using a single intravaginal insert during timed artificial insemination (AI) programs on fertility in lactating dairy cows. A total of 25 randomized controlled studies including 8,285 supplemented cows and 8,398 untreated controls were included in the meta-analysis. Information regarding the presence of corpus luteum (CL) at the initiation of the synchronization protocol was available for 6,883 supplemented cows and 6,879 untreated controls in 21 experiments. Studies were classified based on service number (first AI vs. resynchronized AI), use of presynchronization (yes vs. no), and insemination of cows in estrus during the synchronization protocol (inseminated in estrus and timed AI vs. timed AI only). Reproductive outcomes of interest were pregnancy per AI (P/AI) measured on d 32 (27 to 42) and 60 (41 to 71) after AI, and pregnancy loss between d 32 and 60 of gestation. Random effects meta-analyses were conducted and treatment effect was summarized into a pooled risk ratio with the Knapp-Hartung modification (RRK+H). The effect of moderator variables was assessed using meta-regression analyses. Progesterone supplementation increased the risk of pregnancy on d 32 [RRK+H=1.08; 95% confidence interval (CI)=1.02-1.14] and 60 after AI (RRK+H=1.10; 95% CI=1.03-1.17). The benefit of progesterone supplementation was observed mainly in cows lacking a CL at the initiation of the timed AI program (d 60: RRK+H=1.18; 95% CI=1.07-1.30) rather than those with CL (d 60: RRK+H=1.06; 95% CI=0.99-1.12). Progesterone supplementation benefited P/AI in studies in which all cows were inseminated at timed AI (d 60: RRK+H=1.20; 95% CI=1.10-1.29), but not in studies in which cows could be inseminated in estrus during the timed AI program (d 60: RRK+H=1.04; 95% CI=0.92-1.16). Progesterone supplementation tended to reduce the risk of pregnancy loss (RRK+H=0.84; 95% CI=0.67-1.00). Service number and presynchronization did not influence the effect of progesterone supplementation on fertility. In summary, progesterone supplementation using a single intravaginal insert during the timed AI program increased P/AI mostly in cows without CL and reduced the risk of pregnancy loss in lactating dairy cows. Insemination of cows in estrus during the synchronization protocol eliminated the benefit of supplemental progesterone on P/AI. © 2015 American Dairy Science Association. Source

Considerable progress has been made in reducing starvation during the past century. This was achieved through increased use of arable land and adoption of new technologies. Future increases in food production will depend to a greater extent than in the past on the adoption of new technologies and must be even more rapidly achieved than in the past to meet the increase in demand for food. Intensive industries such as the poultry industry are under pressure from those engaged with a naturalistic fallacy. Technologies such as antibiotics for chickens or hormonal growth promotants (HGPs) for beef cattle that are safe for people, reduce environmental impacts of production, increase profits for producers, and improve animal well-being will be needed to achieve these increases in food production. The precedent set in the EU in banning HGPs can be understood as a response to the illegal abuse of diethylstilboestrol in the EU and as a non-tariff trade barrier to reduce the importation of beef from more efficient producers. The banning of antibiotics in the EU reflects the unwise application of a 'precautionary principle' through which risks were not soundly assessed. However, the unilateral ban established by Coles Supermarkets Pty Ltd on HGPs in Australia represents a more dangerous development, in which marketing ploys have been accorded a higher value than the care of animals, the environment, or the profit made by producers. Decisions such as these have reduced the viability of animal production in the UK and pose a threat to sustainable agricultural production in Australia. © CSIRO 2013. Source

Bramley E.,Murdoch University | Lean I.J.,SBScibus | Fulkerson W.J.,Dairy Farm Consulting | Costa N.D.,Murdoch University
Animal Production Science

Feeding practices in Australian dairy herds were recorded in 100 dairy herds in five districts of two states. A questionnaire about the feeding practices was completed and pasture samples were also collected, where applicable, for analysis. Data and pasture samples were collected once from each farm with visits to regions occurring at different times of the year. Diets were evaluated for nutritional adequacy using the CPM Dairy program. Average milk yield on the day of sampling was 22.8 L/day. The combination of grazed pasture with grain fed during milking was the most prevalent feeding system (54%) in all areas. This was followed by combination of pelleted grain/by-products combined with pasture grazing (25%). Only one herd in the study was not feeding any form of concentrates at the time of sampling. The estimated percentage of concentrate in the diet ranged from 25% ± 11.6 to 44% ± 12.0. Wheat, which was fed at up to 9.8 kg/cow.day DM was the most prevalent grain in all areas, except for Gippsland. The predominant sources of protein in all areas were canola meal, cottonseed meal and lupins. By-products were prevalent, with brewers grain and wheat millrun the most commonly used, fed at 2.8 and 1.6 kg/cow.day DM, respectively. Most farms (81/100) incorporated at least one type of 'buffer' in the ration, and limestone (67%) was the most prevalent mineral additive. Monensin and virginiamycin were fed in all areas, with a varying prevalence. Feeding or dose rates used for minerals and rumen modifiers were not always appropriate to those recommended for mineral needs or control of rumen function. This paper demonstrated that a wide variety of feeding systems are used in Australian dairy herds and provides information on nutritive characteristics of pastures. © 2012 CSIRO. Source

Lean I.J.,SBScibus | Thompson J.M.,University of New England of Australia | Dunshea F.R.,University of Melbourne

This study is a meta-analysis of the effects of the beta-agonists zilpaterol hydrochloride (ZH) and ractopamine hydrochloride (RAC) on feedlot performance, carcase characteristics of cattle and Warner Bratzler shear force (WBSF) of muscles. It was conducted to evaluate the effect of the use of these agents on beef production and meat quality and to provide data that would be useful in considerations on the effect of these agents on meat quality in Meat Standards Australia evaluations. We conducted a comprehensive literature search and study assessment using PubMed, Google Scholar, ScienceDirect, Scirus, and CAB and identification of other studies from reference lists in papers and searches. Searches were based on the key words: zilpaterol, zilmax, ractopamine, optaflexx, cattle and beef. Studies from theses obtained were included. Data were extracted from more than 50 comparisons for both agents and analysed using meta-analysis and meta-regression. Both agents markedly increased weight gain, hot carcase weight and longissimus muscle area and increased the efficiency of gain:feed. These effects were particularly large for ZH, however, fat thickness was decreased by ZH, but not RAC. Zilpaterol also markedly increased WBSF by 1.2 standard deviations and more than 0.8 kg, while RAC increased WBSF by 0.43 standard deviations and 0.2 kg. There is evidence in the ZH studies, in particular, of profound re-partitioning of nutrients from fat to protein depots. This work has provided critically needed information on the effects of ZH and RAC on production, efficiency and meat quality. © 2014 Lean et al. Source

Rabiee A.R.,SBScibus | Lean I.J.,SBScibus | Stevenson M.A.,Massey University | Socha M.T.,Zinpro Corporation
Journal of Dairy Science

The objectives of this meta-analysis were to evaluate the effectiveness of supplementation with the organic trace minerals (OTM; Availa-4 and 4-Plex, Zinpro Corp., Eden Prairie, MN) on milk yield, composition, and component yields and reproductive performance in dairy cows. Twenty research papers and reports on the effects of OTM were considered in this meta-analysis. Criteria for inclusion in the study were information on the form of OTM, an adequate description of randomization, production and reproduction data, and associated measures of variance (SE or SD) and P-values. The OTM increased milk production by 0.93. kg [95% confidence interval (CI) = 0.61 to 1.25], milk fat by 0.04. kg (95% CI = 0.02 to 0.05), and milk protein by 0.03. kg (95% CI = 0.02 to 0.04) per day. Milk SCC was not different in cows supplemented with OTM. All production outcomes except milk solids (yield) and milk SCC were heterogeneous. Meta-regression analysis showed that feeding before calving, feeding for a full lactation after calving, and the use of other supplements increased responses over feeding after calving only, feeding for part of lactation, or not using other supplements, respectively. Supplementation of cows with OTM reduced days open (weighted mean difference = 13.5 d) and number of services per conception (weighted mean difference = 0.27) in lactating dairy cows. The risk of pregnancy on d 150 of lactation was greater in cows fed OTM (risk ratio = 1.07), but OTM had no significant effect on the interval from calving to first service and 21-d pregnancy rate. There was no evidence of heterogeneity for any of the reproductive outcomes evaluated. The results of this meta-analysis showed that organic trace mineral supplementation could improve production and reproduction in lactating dairy cows. © 2010 American Dairy Science Association. Source

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