Growth and meat quality of grain finished entire male Bos indicus cattle

Professor Lee A Fitzpatrick James Cook University - Meat & Livestock Australia

Type: Research Paper
Knowledge level: Advanced

Farm Table says:

This research article looks at growth and meat quality of grain-finished entire male Bos indicus cattle. Interesting to note that animals that met AusMeat specifications for “male” had a ≈$52 higher gross value carcasses than those from castrated animals.

What is the problem?

This project is a good example of producer initiated research in the northern beef industry. It emerged originally as a Producer Demonstration Site (PDS) proposal by the North-west Queensland Regional Beef Research Committee (NWQRBRC), following some personal experience with producing beef from feedlot finished young entire-male cattle by the late Mr. Zanda McDonald, who was Chair of the NWQBRC at the time. Meat and Livestock Australia (MLA) staff, who manage MLA’s research and development program for the north Australian beef industry, recognized that the scope and scale of the proposal were beyond that of a PDS, and so approached James Cook University (JCU) to manage the project.

This research target was to:

• Test the hypothesis that entire male Bos indicus cattle from a north Queensland breeding herd, when grown out to ≈300 kg live weight and finished at ≈460 kg live weight by grain feeding for a minimum of 70 days in a feedlot, would produce a carcass of comparable characteristics and eat quality to that of early- and late castrated males.

• Estimate the economic returns, production parameters, feedlot performance, carcass characteristics, eating quality and animal welfare and behavior issues associated with early and late-castrated, short-scrotum and entire male calves, that have been sourced from northern breeding herds and grain finished.

• Construct a plan outlining future possible marketing and research strategies which will support the findings of this research.

What did the research involve?

Experimental design

-The project was conducted in an experimental design incorporating four (4) male treatments. In the second mustering round at Rutland Plains and Dunbar (late September/early October 2008), entire male calves were weighed and allocated at random to one of four (4) treatment groups, as follows:

• Early-castrate: to be surgically castrated at 1 – 4 months of age

• Late-castrate: to be castrated at weaning at ≈200 kg live weight (≈9 – 12 months old)

• Short-scrotum: to undergo a rubber banding procedure at 1 – 4 months of age to produce short-scrotum entire males (artificial cryptorchid)

• Entire: to remain intact for the duration of the experiment

Project staff

-In addition to the Chief-investigator, Co-investigators and associated technical staff, the project employed a research officer and appointed a Masters by Research (MSc) graduate student, Mr. Steven Wainewright, to assist with the conduct of the project.

Conduct of the project

-In late-September/early-October 2008, the Chief Investigator accompanied by technical staff from JCU and the project research officer worked at Rutland Plains and Dunbar alongside MDH staff to weigh, identify and allocate at random, male calves to treatment groups such that groups were balanced across the range of calf weights and property of origin.

Purchase of steers from MDH and custom feeding

-The project cattle were purchased from MDH Pty Ltd by JCU with project funds, at the time of entry into the feedlot. MDH delivered the project cattle to Wallumba feedlot on 13 July 2010, where they were allocated at random to one of three adjoining pens (176 per pen). and they were inducted into the feedlot on 16 July 2010.

Sale of trail cattle and reimbursement of MLA

-On 26 September 2010, after 75 days on feed, 526 head were trucked to JBS’s Dinmore plant, where they were slaughtered the following day.

Behavioural studies

-It was not logistically possible to record formal behavioral data from paddock studies.

MSA carcass evaluation

-The MSA grading model assigns one of four eating quality grades (2-star = unsatisfactory, 3- star = “good every day”, 4-star = “better than every day”, or 5-star = “premium”) to 40 individual carcass muscles cooked by up to six alternative methods.

Assessment of meat quality

-Animals were ranked in ascending order of Tenderness MVP and then 40 animals from each treatment group were allocated at random for evaluation of meat quality, resulting in a spread of MVP values in each of the treatment groups.

5 Statistical methods

Growth data

-The analysis method used to analyze live weights was a REML model in Genstat (Genstat 2011) with animal ID as the random effect.

Carcass data

-The analysis method used to analyze the carcass data of was one-way ANOVA models in Genstat, with treatment group as the factor.

Genetic data

-The analysis methods used to analyze the impact of genetic factors, Marbling MVP and Tenderness MVP, on related outcomes were linear models and general linear models using Genstat, with treatment group as the factor and the interaction between treatment group and the genetic factors also considered.

Post-mortem pH decline data

-A REML model (GenStat 2011) with animal ID as the random effect was used to analyze post-mortem pH declines.

Predicted meat quality (PMQ) data

-The analysis method used to analyze all outcomes was a REML model in Genstat with animal ID as the random effect.

Objective and sensory test data

-The analysis method used to analyze all outcomes was a REML model in GenStat with animal ID as the random effect.

MSA star grade

– For the animals that were selected for taste panel sensory testing of meat quality, MSA Star Grades were determined either from the boning group data derived from MSA carcass grading (MSA1-BG), the PMQ data generated by the MSA Model (MSA2-PMQ).

What were key findings?

Growth and feedlot data

Liveweights at allocation to treatment groups

-As might be expected, if animals were allocated to treatment groups at random, there were no differences in mean live weights between the groups.

Liveweights at weaning

-There were no differences in mean live weights at weaning between animals in the four treatment groups.

Liveweights, carcass characteristics, and behavioral traits prior to feedlot entry

-There were no live weight differences between the treatment groups on March 2010 when the cattle were yarded to facilitate a subset of animals (25 per group) undergoing ultrasonography to measure fat depth at the 12/13th rib, P8 fat depth, and eye muscle area.

Feedlot performance

-Weather conditions were not conducive to good live weight gains, particularly through the later period of feeding, with a large amount of unseasonal rainfall.

Animal Behaviour

Paddock – In all cases it was reported that behavior, and in particular riding or fighting behavior, of the trial cattle did not differ from that which might be seen among a similar size group of steers under similar conditions.

Feedlot – Riding and fighting behaviors were at a very low level among animals in all treatment groups across the duration of the recording and there were no differences in behaviors observed between the treatment groups.

Carcass grading data from vendor feedback sheets

-About 30% of the carcasses from non-castrated animals were graded as “bull” following slaughter, compared with less than 1% of carcasses from castrated animals.

Sex effects

-There was an association between Sex (M = male or B = bull, where “M” represented castrated or non-castrated animals not showing secondary sex characteristics, and “B” represented animals showing secondary sex characteristics) and Dentition (Pearson ChiSquare = 10.410, DF = 2, P-Value = 0.005).

Chiller assessment and MSA grading

Genetic data

-There was no effect of Marbling MVP or the treatment group and Marbling MVP interaction on USAMB or AUSMB (binary outcome). There was an effect of Tenderness MVP on the sensory test measure, Tender – an effect which also differed across the treatment groups, as evidenced by the interaction between treatment group and Tenderness MPV.

Ossification

-Ossification scores differed between treatment groups (P<0.001).

Meat quality test results

Shear force test

-Age (post-slaughter age of the muscle) or Marbling MVP. Striploins from castrated animals had lower shear force test results than did striploins from non-castrated animals.

Sensory testing

-The MSA sensory testing protocols deliver outcomes for the evaluation of muscles as Tender, Juicy, Flavour, Overall like, MQ4 (meat quality, four variables) and Satisfaction.

MSA Star grades

-For eye rounds (EYE), MSA1-BG was not able to distinguish star grades, with all muscles being rated as star grade 2, whereas 21% were rated as star grade 3 by MSA2-PMQ, and 24% were rated 3 by MSA3-MQ4.

Economic modeling

-An economic case study of entire-male grain-fed beef from a north-west Queensland production system was undertaken by Steven Wainewright as part of his Masters by Research graduate student program associated with the project.

Graduate research student outcome

-Mr. Steven Wainewright successfully completed his research masters degree program at JCU and was awarded the Master of Tropical Animal Science degree in December 2012.

Liveweight and carcass composition

-There were no differences in live weights or weight gains between the treatment groups prior to their entry to the feedlot, although there were some minor differences in weight gains at various times from branding to trucking to the feedlot.

Behaviour

-There were no detectable behavior differences between the treatment groups at any time. Stockman who worked with the cattle in the yards and paddock observed that their behavior was not dissimilar to that of uniform mobs of steers of similar ages.

Carcass grading data from vendor feedback sheets

-Only one animal from each of the Early-castrate and Late-castrate treatment groups (0.7%) was graded as “bull”, compared to 34 animals from the Short-scrotum (28%) and 43 animals from Entire (36%) treatment groups.

Gross returns

– Interestingly, the mean gross value of the carcasses did not differ between the treatment groups.

Final comment

A building of young entire Bos indicus males has the potential for substantial returns for northern beef producers with little impact to meat quality. However, there is a need for further data to be generated to allow the MSA grading model to be further refined for high-grade Bos indicus cattle.

2014 - Australia - Professor Lee A Fitzpatrick James Cook University - Meat & Livestock Australia
Read ArticleSave For Later

Related Resources