A pelleted diet containing camelina hay (CAMH) or camelina meal (CAMM) as a supplement along with a control pellet (CONT) diet formulated with commonly available feeds during summer was used to investigate an alternative pathway for sustainable meat production. Sustainable meat production was based on a simple estimation of income from meat produced versus feed costs if animals were fed for an extended period over summer compared to early slaughter at the beginning of summer. Eighty maternal composite wether lambs (Composite) based on Coopworth genetics and 80 pure Merino wether yearlings were divided into 10 groups within breed (n = 8) using stratified randomisation based on liveweights. Following 1 week of adaptation to experimental diets, animals were fed experimental diets for up to10 weeks. Animals were slaughtered after either 8, 9 or 10 weeks of full feeding when the average liveweight of diet/genetic combination reached a weight appropriate for either ‘heavy lamb’ or ‘heavy hogget’ production, which occurred between 8 and 10 weeks of full feeding. There was no diet × breed interactions except for dressing percentage (DP), where Composite lambs fed the CAMH diet had the greatest DP (48.1 ± 0.35) and the Merino yearlings fed the CAMM diet the lowest DP (45.8 ± 0.33). Composite lambs gained 17.6–20.3 kg and Merino yearlings gained 10.7–12.9 kg liveweight. Based on their DP, this resulted in the production of approximately 8.3–9.5 kg additional carcass weight in Composites and 4.9–5.7 kg in Merinos, which in turn produced greater profit per Composite lamb and a small profit per Merino yearling. Composite lambs fed CAMM and CAMH had 5% greater carcass weights at slaughter compared to the CONT group, but dietary treatments did not change carcass weight of Merino yearlings at slaughter. The extended feeding approach offered the producer an estimated economic gain of AUD $20.00 to $25.00 when yearly average prices were used (Method 1) and AUD $40.00 to $47.70 when pre- and post-summer average prices were used (Method 2) per Composite lambs, but extra carcass gain did not result in the same profit per Merino yearling. Among the Composites, the profit for animals fed the CAMH and CAMM were AUD $2.75 to $4.50 greater than CONT group when full year average prices were applied while AUD $3.50 to $5.50 greater than CONT group when pre- and post-summer average prices were applied. However, we acknowledge a combination approach of extended feeding for a portion of animals already on ground and selling the remaining animals pre-summer with joining of additional ewes is the most likely strategy. Considering the scenario of extended feeding for 3 weeks, based on the growth rates observed for Composite lambs, if an additional 2 kg carcass weight per animal can be gained for 50% of the 22 million lambs slaughtered in Australia (= 11 million animals), it would potentially supply an additional 22 million kg of lamb carcasses produced per annum. This is equivalent to producing an extra 1 million lamb carcasses per annum weighing 22 kg each. Feeding Composite lambs for an extended period and selling Merino yearlings pre-summer may be a good option due to faster growth rate of Composites that may help quick turn-over to market.

中文翻译：

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可持续羊肉生产的替代方法：对粮食安全的影响。

使用包含亚麻干草 (CAMH) 或亚麻荠粉 (CAMM) 作为补充剂的颗粒饲料以及使用夏季常用饲料配制的对照颗粒饲料 (CONT) 来研究可持续肉类生产的替代途径。可持续肉类生产是基于对肉类生产收入与饲料成本的简单估计，如果动物在夏季喂食较长时间，而不是夏季开始时的早期屠宰。基于 Coopworth 遗传学和 80 只纯美利奴一岁鸽在品种内使用基于活重的分层随机化将 80 只母体复合天气羔羊（复合）分为 10 组（n = 8）。在适应实验饮食 1 周后，给动物喂食实验饮食长达 10 周。动物在 8 点后被屠宰，当日粮/遗传组合的平均体重达到适合“重羊肉”或“重猪”生产的体重时，全饲喂 9 或 10 周，这发生在全饲喂 8 至 10 周之间。除了饲喂百分比 (DP) 外，没有日粮×品种相互作用，其中饲喂 CAMH 日粮的复合羔羊的 DP 最高 (48.1 ± 0.35)，饲喂 CAMM 日粮的美利奴一岁鸽的 DP 最低 (45.8 ± 0.33)。复合羔羊体重增加了 17.6-20.3 公斤，美利奴一岁鸽体重增加了 10.7-12.9 公斤。根据他们的 DP，这导致复合材料的胴体重量增加了大约 8.3-9.5 公斤，美利奴羊的胴体重量增加了 4.9-5.7 公斤，这反过来产生了每只复合羔羊的更大利润和每只美利奴一岁鸽的小额利润。与 CONT 组相比，饲喂 CAMM 和 CAMH 的复合羔羊在屠宰时的胴体重量增加了 5%，但日粮处理并未改变美利奴一岁鸽在屠宰时的胴体重量。当使用年平均价格（方法 1）时，扩展饲喂方法为生产者提供了 20.00 至 25.00 澳元的估计经济收益，而在使用夏季前后平均价格（方法 2）时，每只复合羔羊的经济收益为 40.00 至 47.70 澳元，但额外的胴体增益并没有为每只美利奴一岁鸽带来相同的利润。在复合材料中，当采用全年平均价格时，喂养 CAMH 和 CAMM 的动物的利润比 CONT 组高 2.75 至 4.50 澳元，而在采用夏前和夏后平均价格时，比 CONT 组高 3.50 至 5.50 澳元。然而，我们承认，最可能的策略是对已经在地上的部分动物进行延长喂养，并在夏季前出售剩余的动物并加入更多母羊的组合方法。考虑到延长喂养 3 周的情况，根据观察到的复合羔羊的生长速度，如果在澳大利亚屠宰的 2200 万只羔羊中的 50%（= 1100 万只动物），每只动物的胴体重量可以增加 2 公斤，它可能会额外供应每年生产的 2200 万公斤羔羊胴体。这相当于每年额外生产 100 万只羔羊胴体，每只重 22 公斤。长时间饲喂复合材料羔羊并在夏季前销售美利奴一岁鸽可能是一个不错的选择，因为复合材料的增长率更快，可能有助于快速进入市场。