Search

The objective of this study was to determine the effect of offering animals a multi forage choice (MF) of fresh herbages on dry matter intake (DMI), live weight gain, and animal welfare, in comparison with a monotonous diet of ryegrass (Lolium perenne L.). Twenty ram lambs (30.5 ± 0.9 kg initial live weight; mean ± SEM), were randomly allocated to either a diet consisting of diverse MF choice or a single forage ryegrass (SF) diet (n = 10 per treatment) for 35 d. Both diets were fed ad libitum; however, the MF diet was composed of set dry matter ratios of 24% chicory (Cichorium intybus L.), 30% lucerne (Medicago sativa L.), 25% plantain (Plantago lanceolata L.), and 21% ryegrass. The DMI of the MF lambs was 48% greater (P < 0.01) and the within animal day-to-day coefficient of variation (CV) of intake was 26% lower (P < 0.01) than the SF lambs. The average daily gain (ADG) of lambs offered the MF diet was 92% greater (P < 0.01) than the lambs offered the SF diet. The within-animal day-to-day CV of intake was negatively related to ADG (r = −0.59; P < 0.01). The MF lamb’s urinary N concentration was 30% lower (P < 0.01) than that of the SF lambs. The SF lambs spent more time (P < 0.05) exhibiting stereotypic behaviors in the afternoon and spent more time observing other animals than the MF. Overall, allocating an MF choice of fresh herbages as opposed to a single forage diet of ryegrass increases DMI and thereby animal performance, while potentially reducing urinary N excretion. [ABSTRACT FROM AUTHOR]

Urine nitrogen excretion (g/d; UN) represent a significant environmental impact for both confinement feeding and pastoral based dairy systems. It is difficult to measure UN directly due to animal handling and labor requirements, especially in forage based production systems. The currently available milk urea nitrogen (MUN) equations have been shown to overestimate UN excretion of grazing dairy cows compared with an equation using urinary creatinine and UN concentration, indicating that diet may alter the relationship between MUN and UN. This potential was explored using data retrieved (treatment means: n = 69 and 27 for fresh forage [FF] and total mixed ration [TMR] fed cattle, respectively) from the literature and new data obtained from dairy cows fed FF (n = 15) in metabolism crates was used to test the new equations. The TMR data from literature was further split into a training set (to develop the model; n = 53) and a test set (to validate the model; n = 16). There was an interaction for diet type (P < 0.01) where UN (g/d) = 0.023 × MUN (mg/dL) × live-weight (kg, LW) for TMR fed cattle, (similar to a pre-established equation); however, UN (g/d) = 0.015 × MUN × LW for FF fed cattle. For FF based equations, the New MUN equation and the creatinine equation showed good precision and accuracy (Lin's CCC = 0.79 and 0.74, respectively) and adequate predictive ability (RMSEP = 29.8 and 35.9, respectively). The new MUN equation for TMR fed cattle showed excellent accuracy and precision (Lin's CCC = 0.87) with good predictive ability (RMSEP = 24.3) for UN excretion (observed mean = 216.5 g/d). The new equations generated during this meta-analysis provide promising predictive ability of UN excretion, which can be used for management considerations, future research, and policy making. [ABSTRACT FROM AUTHOR]

The current experiments were conducted across two lamb finishing seasons (2019 [experiment 1; Exp1 ] and 2020 [experiment 2; Exp2 ]). In both experiments lambs were provided a monotonous ( MON ) diet (annual ryegrass [ Lolium multiflorum L.] during 2019 and perennial ryegrass [ L. perenne L.] and white clover [ Trifolium repens L.] during 2020) or a diverse ( DIV ) diet composed of spatially separated strips sown to chicory ( Chicorium intybus L.), plantain ( Plantago lanceolata L.), perennial ryegrass, lucerne ( Medicago sativa L.), and dock ( Rumex obtusifolius ). During Exp1, the DIV lambs had a stocking rate ( SR ) of either 80, 95, 100, or 110 m 2 /lamb/wk, whereas the MON lambs had a 100 m 2 /lamb/wk SR. In Exp2, the SR aimed to allocate the MON lambs with twice the forage allowance (kg DM/lamb/d) as DIV lambs. In Exp1, all lambs provided DIV had a greater ( P  < 0.01) average daily gain ( ADG ; + 130%) than MON rams, independent of the SR. Accordingly, DIV had greater ( P  < 0.05) hot carcass weight ( HCW ; + 26%) and aged carcass weight ( CW ; + 27%) compared with MON, across all SR. The 80 m 2 /lamb/wk SR tended to have a greater ( P  = 0.10) dressing percentage and had similar ( P  = 0.29) drip loss percentage to the MON lambs, while the other DIV lamb SR all had greater ( P  < 0.05; +12%) dressing percentages and lower ( P  < 0.05) drip loss percentage than MON lambs. In Exp2, DIV lambs had greater ( P  < 0.01) ADG (+37%), HCW (+15%), and dressing percentage (+6%) compared with MON lambs. This improved animal performance occurred despite being offered 57% less ( P  = 0.01) dry matter ( DM ), 56% less ( P  < 0.01) digestible DM, and 57% less ( P  = 0.02) metabolizable energy per lamb per day. Ultimately, these experiments demonstrate that providing growing lambs a functionally diverse diet improves animal growth performance and carcass weight compared with a monotonous diet of annual ryegrass or a mixed sward containing perennial ryegrass with white clover., Competing Interests: None declared., (Published by Oxford University Press for the American Society of Animal Science 2024.)