PSIV-12 Effects of feeding a novel alfalfa leaf pellet product (ProLEAF MAX™) and alfalfa stems (ProFiber Plus™) on production of lactating dairy cows

Alfalfa is a commonly grown forage in the Intermountain west and is often included in lactating dairy cow rations. This study investigated the effects of including novel alfalfa products: ProLEAF MAX™ (PLM), an alfalfa leaf pellet; and ProFiber Plus™ (PFP), alfalfa stems, in the diet of lactating dairy cows on dry matter intake, milk yield, and milk components. Holstein cows were housed in a freestall barn and milked in a free-flow automatic milking system. All cows were fed each treatment for 21-days, then switched to the next treatment utilizing a crossover experimental design. The five treatments were: control (CON, typical diet including alfalfa hay; n = 65); low-quality alfalfa hay (LQ+PLM, a diet that replaced alfalfa hay with low-quality alfalfa hay and PLM; n = 62); PLM+PFP (a diet that replaced alfalfa hay with PLM and PFP; n = 65); PLM (a diet that replaced alfalfa hay with PLM; n = 62); and PFP (a diet that replaced alfalfa hay with PFP; n = 60). Cows were group fed a partial mixed ration balanced for 40.8 kg milk, 3.9% milk fat and 3.3% milk protein. Individual milk yield and milk components were recorded daily by the automatic milking system. Dry matter intake was also recorded daily. When fed the PFP diet, cows had decreased (P < 0.01) dry matter intake compared to the other diets. Milk yield was increased (P < 0.01) when cows received the PLM diet when compared to the other diets. When fed the PFP and PLM+PFP diets, milk fat was increased (P < 0.01) when compared to the other diets. Milk protein was decreased (P < 0.01) when cows were fed the PFP diet when compared to the other diets. These data indicate that inclusion of fractionated alfalfa products in the diet of lactating dairy cows has the potential to increase milk yield and milk components.

Effects of feeding a novel alfalfa leaf pellet product (ProLEAF MAX) and alfalfa stems (ProFiber Plus) on performance in the feedlot and carcass quality of beef steers

Alfalfa is often included in the diets of beef animals; however, the nutrient content of alfalfa is variable depending on the region in which it is grown, climate, soil, and many other factors. The leaf portion of alfalfa has a less variable nutrient composition than the stem portion of the plant. The variability that is present in the alfalfa plant can make the development of total mixed rations of consistent nutrient content difficult. As such, the purpose of this study was to determine how inclusion of fractionated alfalfa leaves and alfalfa stems impacts performance and carcass quality of finishing beef steers. Twenty-four steers were allocated to one of three treatments: a control group fed a typical finishing diet with alfalfa as the forage (CON; n=8), a typical diet that replaced alfalfa with fractionated alfalfa leaf pellets and alfalfa stems (ProLEAF MAX™ + ProFiber Plus™; PLM+PFP; n=8), or a typical diet that replaced alfalfa with alfalfa stems (PFP; n=8) for 63 days. Steers were fed individually once daily, weighed every 14 days and ultrasound images were collected every 28 days. At the end of the feeding trial, steers were harvested at a commercial facility and carcass data was obtained. Analysis of dry matter intake demonstrated that steers receiving the PFP and CON diets consumed more feed (P < 0.001) than steers consuming the PLM+PFP diet. Steers receiving the PLM+PFP diet gained less (P < 0.001) weight than the steers receiving the other two dietary treatments. No differences (P > 0.10) in feed efficiency or carcass characteristics were observed. Steers receiving the PFP diet had improved (P = 0.016) cost of gain ($0.93 per kg) when compared to steers receiving PLM+PFP ($1.08 per kg) diet. Overall, our findings demonstrate that inclusion of PFP in place of alfalfa hay in a finishing diet has the potential to improve cost of gain, without negatively affecting growth, performance, or carcass characteristics of finishing feedlot steers.

Alfalfa leaf curl virus is efficiently acquired by its aphid vector Aphis craccivora but inefficiently transmitted

Alfalfa leaf curl virus (ALCV) is the first geminivirus for which aphid transmission was reported. Transmission by Aphis craccivora was determined previously to be highly specific and circulative. Using various complementary techniques, the transmission journey of ALCV was monitored from its uptake from infected plant tissues up to the head of its vector. ALCV was shown to be restricted to phloem tissues using fluorescence in situ hybridization (FISH) and electropenetrography (EPG) monitoring of virus acquisition. Furthermore, the virus is heterogeneously distributed in phloem tissues, as revealed by FISH and quantitative PCR of viral DNA acquired by EPG-monitored aphids. Despite the efficient ingestion of viral DNA, about 106 viral DNA copies per insect in a 15 h feeding period on ALCV-infected plants, the individual maximum transmission rate was 12 %. Transmission success was related to a critical viral accumulation, around 1.6×107 viral DNA copies per insect, a threshold that generally needed more than 48 h to be reached. Moreover, whereas the amount of acquired virus did not decrease over time in the whole aphid body, it declined in the haemolymph and heads. ALCV was not detected in progenies of viruliferous aphids and did not affect aphid fitness. Compared to geminiviruses transmitted by whiteflies or leafhoppers, or to luteoviruses transmitted by aphids, the transmission efficiency of ALCV by A. craccivora is low. This result is discussed in relation to the aphid vector of this geminivirus and the agroecological features of alfalfa, a hardy perennial host plant.

PSVI-6 Effects of feeding a novel alfalfa leaf pellet (ProLEAF MAX™) and an alfalfa stem byproduct (ProFiber Plus™) on growth and conception rates of developing dairy heifers

Alfalfa is a commonly grown forage in the Intermountain west and is often included in rations for dairy animals. This study investigated the effects of including novel alfalfa products: ProLEAF MAX™ (PLM), an alfalfa leaf pellet; and ProFiber Plus™ (PFP), alfalfa stems, in the ration of dairy heifers on growth, feed efficiency, and conception. Heifers were stratified by weight and farm origin, and randomly allocated to one of three treatment groups (n = 8/treatment): control (CON, typical ration that included alfalfa hay), PLM+PFP (a ration that replaced alfalfa hay with PLM and PFP), or PFP (a ration that replaced alfalfa hay with PFP). Heifers were fed for 84 d in individual pens and feed intake and refusals were recorded daily. Weight, hip height, and wither height were recorded every two weeks and blood was collected every four weeks. Additionally, blood urea nitrogen (BUN) and conception rates were measured. Data were analyzed with day as a repeated measure and treatment as a fixed effect. Heifers fed the CON ration had increased (P < 0.05) weight gain, hip height, and dry matter intake over time compared to the treatment groups. There was a treatment*time (P < 0.05) effect on feed efficiency where heifers fed the PFP had more variable feed efficiency than CON or PLM+PFP. Treatment had an effect (P > 0.03) on BUN where CON heifers had increased BUN compared to those fed PFP. No differences (P < 0.05) were observed in conception. These data provide insight into how performance of growing heifers is affected when novel alfalfa products are included in the ration and indicate that inclusion of PFP might decrease growth of heifers by decreasing DMI. More research needs to be done to determine whether there is an optimal amount of these products to include in heifer rations.

Co-Acquired Nanovirus and Geminivirus Exhibit a Contrasted Localization within Their Common Aphid Vector

Single-stranded DNA (ssDNA) plant viruses belong to the families Geminiviridae and Nanoviridae. They are transmitted by Hemipteran insects in a circulative, mostly non-propagative, manner. While geminiviruses are transmitted by leafhoppers, treehoppers, whiteflies and aphids, nanoviruses are transmitted exclusively by aphids. Circulative transmission involves complex virus–vector interactions in which epithelial cells have to be crossed and defense mechanisms counteracted. Vector taxa are considered a relevant taxonomic criterion for virus classification, indicating that viruses can evolve specific interactions with their vectors. Thus, we predicted that, although nanoviruses and geminiviruses represent related viral families, they have evolved distinct interactions with their vector. This prediction is also supported by the non-structural Nuclear Shuttle Protein (NSP) that is involved in vector transmission in nanoviruses but has no similar function in geminiviruses. Thanks to the recent discovery of aphid-transmitted geminiviruses, this prediction could be tested for the geminivirus alfalfa leaf curl virus (ALCV) and the nanovirus faba bean necrotic stunt virus (FBNSV) in their common vector, Aphis craccivora. Estimations of viral load in midgut and head of aphids, precise localization of viral DNA in cells of insect vectors and host plants, and virus transmission tests revealed that the pathway of the two viruses across the body of their common vector differs both quantitatively and qualitatively.

Alfalfa leaf curl virus is efficiently acquired by its aphid vector Aphis craccivora but inefficiently transmitted

ABSTRACTAlfalfa leaf curl virus (ALCV) is the first geminivirus for which an aphid transmission was reported. Transmission by Aphis craccivora was determined previously to be highly specific and circulative. Using various complementary techniques, the transmission journey of ALCV was monitored from its uptake in an infected plant tissue up to the head of its vector. ALCV was shown to be restricted in the phloem using fluorescent in situ hybridization (FISH) and electropenetrography (EPG) monitoring of virus acquisition. Furthermore, the virus is heterogeneously distributed in the phloem as revealed by FISH and qPCR quantification of the viral DNA acquired by aphids monitored by EPG. In spite of the efficient ingestion of viral DNA, about 106 in a 15-hour feeding on ALCV infected plants, the individual transmission rate was at a maximum of 12%. Transmission success was related to a critical viral accumulation, around 1.6×107 viral DNA copies per insect, a threshold that needs generally more than 48 hours to be reached. Moreover, whereas the amount of acquired virus does not decrease over time in the whole aphid body, it decreased in hemolymph and heads. ALCV was not detected in progenies of viruliferous aphids and had no effect on aphid fitness. Compared to geminiviruses transmitted by whiteflies or leafhoppers or to luteovirus transmitted by aphids, the transmission efficiency of ALCV by A. craccivora is low. This result is discussed in relation to the aphid vector of this geminivirus and the agroecological features of alfalfa, a hardy perennial host plant.