Integrating Camelina Into Organic Pig Production—Impact on Growth Performance of Pigs, Costs, and Returns

The sustainability of organic production and cover crops depends on production costs and the economic value of products. Feed cost, contributing 65–75% of the total production cost, has a significant impact on profitability of organic pig farming. Utilizing grains harvested from cover crops as a feed ingredient for organic pigs can potentially protect the environment and increase the economic value of cover crops. This study was the first to evaluate the viability of integrating winter cover crop, camelina, into organic pig production. Winter camelina was grown organically in single or relay with soybeans to increase the total yield per hectare. Camelina yields in monocrop and in relay-crop fields were 1,394 and 684 kg ha−1, respectively. Although the total yield of camelina and soybean (1,894 kg ha−1) in the relay-crop field was higher than camelina yield in the monocrop field, monocropping camelina is more economical than relay-planting with soybeans due to the difference in production costs. Camelina press-cake was supplemented in diets fed to pigs raised under near-organic standards. Supplementing 10% camelina press-cake in diets reduced feed intake, weight gain, final weight at market, carcass weight, and dressing percent of pigs, but did not affect feed efficiency, belly firmness or pork quality. The viability of integrating camelina into organic pig production depends on marketing organic pigs for $2.4 kg−1 of live weight and marketing camelina oil for $3.59 kg−1 or more if monocropping.

Effects of increasing dietary inclusion of camelina cake on growth performance of growing-finishing pigs

The objective of this experiment was to determine the dietary inclusion rate of camelina cake (CC) that would support the growth performance of growing-finishing pigs similar to that of a corn-soybean meal-based diet. Pigs (n = 192; BW = 35.2 kg; Duroc x (Yorkshire x Landrace)), balanced for sex and initial weight, were assigned to pens (8 pigs/pen) and pens were assigned randomly to one of four dietary treatments (6 pens/treatment). Treatments consisted of a non GMO corn-soybean meal control diet (CON), or CON containing 5% (5CC), 10% (10CC), or 15% (15CC) camelina cake. Feed disappearance on a pen basis and individual body weights of pigs were recorded every other week to calculate average daily gain (ADG), average daily feed intake (ADFI), and gain to feed ratio (G:F) on a pen basis. Prior to harvest, real-time ultrasonic measurements of back fat depth and loin eye area were collected on all live pigs. Pigs were harvested as a single group at about 23 weeks of age at a commercial abattoir. Data were analyzed using Proc Glimmix with dietary treatment as a fixed effect and pen serving as the experimental unit. Growth performance data collected over time were analyzed using repeated measures within the Proc Glimmix procedure. Overall, pigs fed CON exhibited similar ADG to those consuming 5CC and higher ADG than pigs consuming 10CC and 15CC diets (1.10 kg vs. 1.05 kg for 10CC and 1.02 kg for 15CC; P < 0.05 for both mean comparisons). Pigs fed CON consumed more feed than pigs fed any of the CC diets (ADFI = 2.66 kg for CON vs. 2.46 kg for 5CC, 2.46 kg for 10CC and 2.47 kg for 15CC; P < 0.05 for all). These differences resulted in heavier (P < 0.05) CON-fed pigs at marketing than 10CC or 15CC-fed pigs. There were no differences in any carcass traits analyzed. From these data, we conclude that feeding up to 5% CC in corn-soybean meal-based diets did not negatively influence growth performance, or carcass traits of growing-finishing pigs.

Agriculture. Genetically modified crops and farmland biodiversity

The debate about genetically modified crops that are resistant to herbicides and their effects on the environment rages on. In their Perspective, Firbank and Forcella discuss a new model (Watkinson et al.) that seeks to calculate the impact of genetically modified herbicide-resistant sugar beet on growth of the weed Chenopodium album and on the skylark, which feeds on the seeds of this weed.

Manipulation of buried seed reserves by timing of soil tillage in Mediterranean-type pastures

Environmental requirements for seed germination and seedling growth vary appreciably among pasture species. Therefore, it is possible that the botanical composition of pastures may be manipulated by timely seasonal exposure of the soil-seed reserve to conditions that promote germination differentially. This possibility was examined in two Mediterranean type pastures in which plots were tilled once per year, each in a different month, for 2 years. For several pasture species, effects were estimated with respect to numbers of soil seeds, numbers of emergent seedlings and canopy coverage. Individual species showed specific behaviour patterns. Seeds of sorrel (Rumex acetosella) and wireweed (Polygonum aviculare) maintained abundant seed in the soil, those of annual ryegrass (Lolium rigidum) and subterranean clover (Trifolium subterraneum) were less persistent, and seeds of red brome (Bromus rubens) and silvergrass ( Vulpia spp.) occurred only seasonally in the soil-seed pools. Mature plants of red brome, silvergrass and subterranean clover attained dominance only in summer and early autumn-tilled plots. Annual ryegrass was more abundant when soil was cultivated in late autumn and early winter, whereas sorrel and wireweed were significant only in plots ploughed in winter. Thus botanical composition may be altered radically by time of tillage, and this has several practical implications for pasture management and weed control.

A species-area curve for buried viable seeds

A species-area curve was constructed for buried viable weed seeds in a 5-year-old subterranean clover-annual ryegrass pasture in south-eastern Australia. A soil surface area of about 200 cm2 (to a depth of 10 cm) was required to obtain a representative individual sample (i.e. a replicate) of the number of taxa in the soil seed bank, whereas a combined area of about 1000 cm2 was required for adequacy within any treatment. The total number of buried viable seeds of all species combined was distributed spatially in a more-or-less uniform manner. This suggests that a sample whose size is sufficient for determination of species diversity of buried seeds is equally adequate for measuring buried seed density.