The Investigation of depot-specific adipogenesis and lipogenesis in bottle-fed ram lambs.

The deposition of fat in ruminants is a dynamic process that significantly impacts meat quality and production efficiency. The objective of this study was to investigate the dynamics of fat deposition over time across various depots in bottle-fed ram lambs, focusing on pre-adipocyte cell number and gene expression as a key determinants of fat accumulation. Suffolk ram lambs (n = 13) were serially harvested on d 15 (n = 4), d 45 (n = 4), and d 105 of age (n = 5). Lambs were supplemented with milk replacer 20% of body weight (BW)] from d 5 to d 30 of age, milk replacer (10% BW) with creep feed (2.5% of BW) supplementation from d 30 to 45, and creep feed (5% of BW) from d 45 to d 105 of age. At each harvest timepoint, fat depots, including subcutaneous, intramuscular (longissimus muscle), and visceral fat, were snap-frozen for RNA extraction, downstream gene expression analysis, and fatty acid extraction. Pre-adipocyte cells were also preserved, enzymatically digested and subsequently isolated from each depot. Pre-adipocyte cell number was assessed using the CellDrop (Denovix). Preliminary results revealed that pre-adipocyte cell numbers were significantly greater (P < 0.05) in subcutaneous and visceral depots 17-d old lambs in comparison to all other depots in other timepoints. The number of pre-adipocytes in intramuscular adipose depots did not differ over time (P > 0.05). Visceral and subcutaneous adipose depots had a significantly greater (P < 0.05) amount of preadipocytes present in comparison with the intramuscular depot. Total fatty acid content differed (P < 0.05) among depots and timepoints. Omental fat from d 105 lambs exhibited the greatest (P < 0.05) total fatty acid content in comparison with all other depots. Total fatty acid amount did not statistically differ (P > 0.05) between d 17 and d 45 omental fat depots. Total fatty acid content did not differ (P > 0.05) over time in intramuscular fat samples (LM). The gene expression of several proposed pre-adipogenic markers were evaluated across timepoints and tissues. Moreover, the relationship between pre-adipocyte cell number and fat deposition in both subcutaneous and visceral depots indicates their crucial role in overall fat accumulation in ram lambs. These findings offer novel insights into the dynamics of fat deposition in ruminants, emphasizing the importance of intramuscular fat depots as key sites for fat accumulation. Understanding the relationship between pre-adipocyte cell number and fat deposition across depots can inform management strategies aimed at enhancing meat quality and production efficiency in sheep farming systems. Further research is needed to elucidate the molecular mechanisms underlying fat deposition in different depots and its impact on meat quality traits. [ABSTRACT FROM AUTHOR]