8 Differential Growth Performance in Conventionally and Artificially Raised Lambs Fed High-Concentrate and High-Forage Post-Weaning Diets

Autor: Katherine G Parsley, Jennifer R Weinert-Nelson, Donald Ely, Tracy Hamilton, Matthew Hamilton, LeeAnn Jacks, Brittany Harlow
Rok vydání: 2023
Předmět:
Zdroj: Journal of Animal Science. 101:121-122
ISSN: 1525-3163
0021-8812
Popis: Artificial rearing of lambs on milk replacer presents management challenges for producers and can impact performance. The objective of this experiment was to evaluate effects of pre-weaning management on adaptation to post-weaning finishing diets. We hypothesized that lambs fed a high-concentrate (HC) diet would exhibit more efficient body weight (BW) gain than lambs fed a high-forage diet (HF) regardless of pre-weaning management. Thirty-two Polypay conventionally raised (CR; n = 10 rams, 6 ewes) or artificially raised (AR; n =10 rams, 6 ewes) lambs (age: 84.0 ± 0.8 d) were blocked by sex and BW and randomly assigned to either a HC (85:15 concentrate: forage) or HF (50:50 concentrate:forage) finishing diet (n = 8 CR and AR lambs diet-1). Individually housed lambs were fed ad libitum and remained on feed through a target finishing weight of 59.0 or 54.4 kg for rams and ewes, respectively. Feed intake and BW gain were measured at 7-day intervals. Data were analyzed by PROC GLM in SAS (v. 9.4, SAS Inst. Inc., Cary, NC). Initial BW for CR lambs (39.0 ±.9 kg) was greater than for AR (32.9 ± 0.5 kg; P < 0.01), but there was no difference between diets (P = 0.72) or pre-weaning by diet interaction (P = 0.54). Time on feed and average daily gain (ADG) did not differ between diets for CR (time on feed: 48.1 ± 2.8 d; ADG: 206.9 ±1.4 g∙d-1; P ≥ 0.22). In contrast, post-weaning diet did impact time on feed for AR lambs, with longer time on feed for HF (68.9 ± 2.5 d) than HC (56.2 ± 2.4 d; P < 0.01). The ADG was also numerically greater for HC (424 ±9.8 g) than HF (370 ± 24.0 g) for AR lambs (P = 0.11). Dry matter intake (DMI) was less for CR lambs fed HC (35.16 ±.65 g kg BW-1∙d-1) than HF (41.32 ± 0.69 g∙kg BW-1∙d-1,P < 0.01) but did not differ between diets for AR lambs (40.58 ±.35 g kg BW-1∙d-1; P = 0.99). The decreased DMI in CR lambs fed HC resulted in greater feed efficiency (0.26 ± 0.02) compared with lambs fed HF (0.21 ± 0.01; P = 0.03). Feed efficiency did not, however, differ by diet for AR lambs (HC: 0.27 ± 0.02; P = 0.64). Results of this study suggest that CR lambs were better able to adapt to a HF finishing diet than AR lambs. Additionally, CR lambs exhibited superior feed utilization when fed HC in comparison to HF, but this response was not found for AR lambs. Overall, these results demonstrate differential adaptation to HC vs. HF finishing diets in response to pre-weaning management.
Databáze: OpenAIRE
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