Browsing by Author "Wyffels, Samuel A"

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Effects of pelleted versus loose salt-limited protein supplement on supplement intake behavior of yearling heifers grazing dryland pastures
(Oxford University Press, 2022-08) White, Hayley C; Van Emon, Megan L; DelCurto-Wyffels, Hannah M; Wyffels, Samuel A; DelCurto, Timothy
The objectives of this study were to evaluate the impacts of supplement form on supplement intake behavior, body weight (BW), and body condition score (BCS) change of yearling heifers grazing dryland pastures during the summer. In each of the two years, Angus crossbred heifers (14 mo of age; year 1, N = 57, BW = 449 ± 3.60 kg; year 2, N = 58, BW = 328 ± 3.57 kg) were used in a 84-d completely randomized design evaluating the following treatments: 1) control, no supplement; 2) salt-limited supplement in pelleted form; and 3) a salt-limited supplement in loose form. Individual supplement intake, and time spent at the feeder were measured throughout the course of the study using a SmartFeed Pro self-feeder system (C-Lock Inc., Rapid City, SD, USA). On days 0, 42, and 84, the heifers were weighed, and body condition scored following a 16-h shrink. Supplementation and form of supplement did not influence (P ≥ 0.62) BW change for yearling heifers within or across study grazing periods. Body condition score was not influenced (P ≥ 0.26) by supplementation and form within the 0 to 42 (period 1) or 42 to 84 (period 2)-d periods but displayed a treatment by year interaction (P < 0.01) for the 84-d summer grazing period. Supplement intake (kg/d and g/kg BW) displayed a treatment × period interaction (P < 0.01). Supplement intake (kg/d) of heifers consuming pelleted supplement was 28% and 31% greater (P ≤ 0.02) than heifers consuming loose supplement in periods 1 and 2, respectively. Supplement intake (g/kg BW) of heifers consuming pelleted supplement was 24% and 32% greater (P ≤ 0.05) than heifers consuming loose supplement in periods 1 and 2, respectively. Overall, across both years, supplement intake in period 1 was less than half (P < 0.01) that of period 2, averaging 0.50 and 1.14 kg/day, respectively. Variation in supplement intake (% CV) was greater (P = 0.03) in period 1 compared to period 2, averaging 119% and 91%, respectively. In addition, variation in supplement intake was greater (P = 0.03) in year 2 than year 1, averaging 122% and 88%. Our results suggest that salt-limited supplements have a high degree of intake variation and pelleting could have a masking effect as indicated by the greater intake and intake rate of supplement with heifers consuming the pelleted supplement.
Influence of residual feed intake and cow age on dry matter intake postweaning and peak lactation
(Oxford University Press, 2021-11) Parsons, Cory T; Dafoe, Julia M; Wyffels, Samuel A; DelCurto, Timothy; Boss, Darrin L
Supplemental nutrition for cattle is the greatest operating cost for cow-calf producers, accounting for 65% of the annual expenses (Meyer et al., 2008). Therefore, selection pressure for efficient animals that have lower feed intake but maintain production, or average intake with higher production, could have positive impacts on cow–calf profitability (Meyer et al., 2008). Thus, improving feed efficiency through genetic selection holds significant opportunity for the beef industry. Residual feed intake (RFI) is currently being used as a selection tool for purchasing and retaining heifers and for selecting bulls and semen. Most studies have used steers and terminal heifers when evaluating RFI impact on various aspects of beef cattle production (Kelly et al., 2010). Additionally, the majority of RFI studies have included energy-dense diets and rations focusing on feedlot performance (Lawrence et al., 2011). However, the use and relevance of RFI as a selection tool for the commercial cow–calf industry needs further research (Manafiazar et al., 2015). Research pertaining to RFI of cattle offered forage-based diets is limited (Arthur et al., 2005), with even fewer data available related to beef cattle forage-based production systems (Meyer et al., 2008). As a result, more research is needed to evaluate the utility of RFI estimates on the beef production in extensive forage base systems (Kenny et al., 2018). Therefore, the objectives of this study were to evaluate the influence of heifer postweaning RFI and cow age on dry matter intake (DMI), intake behavior, as well as milk production of dry-lotted black Angus beef cows. We hypothesized that heifers identified as low RFI eat less and the influence of RFI may interact with cow age.